I have many friends who are intrigued by Linux but after 1st attempt to install any Linux brand (dual-boot), they usually give up! Which is sad and IMO one of the biggest reasons Linux does not have a wider user-base WW than it currently have! (Is it about 10% of the world market?)

A single install directly on the C drive, they can do alright just by clicking through the standard flow.

BUT!: The Linux OS developers/programmers have to focus more on the fact that most/many users do not want to abandon WIN/MAC (or whatever other OS they may have running) right away, because their whole computer-life is concentrated in that OS.

They wish to install Linux alongside their WIN/MAC OS, and then later, when they are more confident with their new Linux OS, and they decide that Linux can fulfill all their desires/needs, they might abandon WIN/MAC.

For this to happen, the installation of a Linux flavor alongside a WIN/MAC OS has to be 'easier'!
Even I - as a seasoned Linux user - sometimes mess up installing a nix OS alongside my WIN OS (which is usually already running on the PC of my choice), and it is mostly because I select to put the boot-loader in the wrong place, so that after the installation is done and I reboot - the PC shows the dreaded grub: prompt and some message about cannot find the boot-loader..

So my point with this post is to draw focus on making the various Linux flavors much easier to install as dual-boot than currently - to non/new-Linux users!
Especially the partitioning and boot-loader has to be bulletproof. Also focus on if a user wish to install their /home dir on another drive, be it external USB drive or another drive in the PC.

I have many friends telling me that they gave up on Linux due to those factors. That's not good for the wider audience adoption of Linux.

If Linux want to grow WW then this topic needs to be attended!

I have found ubuntu seems to work first time all the time. That said ubuntu canonical and freedom may no longer be logically compatible.

I doubt there is anything "Linux OS developers/programmers" can do.
It really is not possible, for example, for them to know or in any way work out which drive you would like the bootloader on -- as things stand with a BIOS system things are as easy as they can be when the distributions ask whether the boot loader should go on the MBR of the first drive. How else could this be done?
With UEFI things are a little odd but, then again, there isn't much which can be done by anybody involved in Linux since they don't write UEFI. Some machines, like the one I am typing this on, allow one to boot any partition with a valid boot loader from UEFI so all that needs to be done is to create some partitions for Linux and install it (this being the only bit I think could be made easier in some distributions by creating BIOS and UEFI partitions by default) then change the boot device to the Linux UEFI partition. Others need Secure Boot for Windows and need "shims" and all sorts of messing about to install -- this is dictated by the OEM and cannot be controlled in any way by Linux developers.
I actually do agree that dual booting can be too difficult, by the way, I just don't see that there is much anybody can do about it beyond what is being done.

Use a 'live' system until you feel able/want to install it,that is one of the reasons they exist.

I have not really observed such a problem.
Then only issue I have seen in dual boot install is that Windows may have dropped "that which cannot be moved" right in the way of resizing the NTFS partition to make the room I want for linux. Where that is not a problem, it "just works"! I like "just works". A LOT!

But perhaps my experience is not typical. What Linux distributions have you observed a dual-boot install problem with?

Thx for the answers/reflections guys.

Regarding the position of the boot-loader (which is a crucial step) I would imagine it to be a good idea if it would be possible to bring up a warning if you select to install the boot-loader on a 'wrong' drive from where it will not be possible to boot your PC?
With the MBR on the first drive (if you have eg. WIN installed) and the default Linux choice is to install boot-loader there, when you actually install the Linux OS onto another drive, it becomes confusing to friends where to install the boot-loader, and if picking wrong place, the PC becomes unable to boot, so they may give up on the Linux attempt.

One of the things I think could attract more users is simplifying the partition stuff. (some may state that it's already simple enough)
I often hear from friends that they have no idea of which and how many/how big partitions to make. If they need to make swap, root, boot and so forth - and if they want home to be on another drive, how to do that during install.

But OK as some of you point out - there is not much to do about this - install is optimized as much as it can be.
My observation though, getting feedback from my friends, is that Linux is too difficult to install alongside another OS, and thereby the Linux community loose out on new potential users.
To get a feel of how the Linux OS looks like is OK by running a Live system, but running a Live system until able to install is not a good solution as people want to have it running installed to fully compare.

Anyway I just want to ponder a bit over the task of increasing the WW user-base of Linux.

I've never had any problem with dual booting, and I've been doing it for decades. Well, that's not entirely true, I have had problems, but only when I was mucking around and got myself into a mess. If you have two disks, you can install Linux on one disk by itself, including the boot loader, and use your BIOS boot time disk selector as a OS selector, instead of grub, assuming your BIOS has that feature. It's often F8 at boot time. If you want them on the same drive, I recommend you install Windows first, and make sure to only use part of the disk for Windows. Then install Linux on the remainder of the disk, and most distros will automatically find the Windows partition and add it as a "chain boot loader" in grub.

@digdogger
This is not a thread about me not knowing how to install dual-booting OSes, so no need to try to be 'helpful'.
I myself know how to do it.

If you scroll back up and read my OP, and read all of it, you will understand that this is not focused on people like yourself who knows how to do it.
It is focused on people who don't know Linux when they try install dual-boot, fail and then give up on Linux.

It would be nice if there were some "magic way" to automate dual-boot installations. Making it fast and easy would be sweet for more than just new migrations.

In perspective, however, there are very few other operating systems that allow dual boot at all. The ones that do are not very accommodating of dual booting with a very DIFFERENT OS. (SOME versions of Windows will allow a different version of Windows, but not many) To my knowledge only Linux makes it at ALL friendly. Only Linux INTENTIONALLY makes room for different and pre-existing installs.

With recent advances in virtualization, the question may be moot. Running Linux under windows, or Windows under Linux, has gotten even easier than dual booting. Only raw access to resources and native iron performance for games and power applications (such as video rendering) really cry for a native iron install.

Still, if someone finds or makes that "magic way" to make dual-boot easier, I want to help beta test and hacve early access.

@wpeckham
Ah yes - that's a good point!
I didn't really think of including the VM option in my OP - but yes, that would be an alternative option indeed

I ditched Windows ages ago, so all my dual-booting with it was pre-UEFI/Secure Boot. So it might be trickier, but not impossible, these days. Once I'd done enough research, I found it easy enough. Do research, read and follow instructions, don't blindly leap into it. If you're not willing to make some effort - stick to Windows.

@brianL

again: this thread is not about me needing advice or not knowing how to dual boot.
It is a thread about those who don't know anything about Linux and want to try it but give up because they don't want to get rid of WIN before they have tried a Linux installed on their HW, which is too complex for them to do.

My advice wasn't aimed at you, but those you claim find dual-booting too complex.

IMHO, a far better solution is to use an external (USB3 or FireWire-attached) disk drive. Most computers have the ability to boot from such a drive, maybe by just holding-down a certain key on the keyboard. You simply install your Linux(es) there. You don't touch a single thing about the default installation. Problem solved. You can buy external drives with terabyte capacity for a hundred bucks or so at any office supply store, and "daisy-chain" many of them off a single port. The speed is virtually the same as built-in.

I guess you and I are in agreement?Their failure should be attributed to 'part of the learning process' that is Linux, not blame that failure on it.
It could have easily been OS/2, or a modern MAC.

I failed terribly my first time and needed an experienced "Linux 'guy'".
Couldn't grok the principle of "slices" ('twas a 'BSD flavor, IIRC).
I'm glad Linux isn't easier to install. It's a skill that I acquired through many, many installs of it.
I've earned my "SysAdmin" Title.