I frequent several other forums, and today I read this interesting post on SoundOnSound.com: (a British music site)
Unfortunately, what this person is saying is true ... and, continues to be true. We all remember the hubub that AdSense made back in 2011/2012 (when there were about 600,000 apps in Apple's App Store and Google Play was just getting started), to the effect that more than 60 percent of those apps had never been downloaded at all. Other sources since then have said the same. Less than 1 of apps are financially successful, according to a 2014 article, and one app (Candy Crush) which they cited at that time makes its money by being a very-expensive (but ... coin-box-toting) arcade video game.

Hopeful writers of e-books and iTunes find that they have much the same experience. Not only is it virtually impossible to let users know that your product exists, consumers are firmly conditioned to expect(!) that your product either is free, or damn-nearly so. ("In exchange for my $0.99, I expect you to support me for life.") Articles repeatedly say that these authors of various things wind up making less than $1,000 a year ... and some said, less than $100.

I guess I've been lucky to be selling a niche software product ... more-or-less continuously since 1996, believe it or not ... but today it costs between $150 and $450 (USD) a copy, and $35 to try it out for 30 days (this applicable to a purchase within that time). The non-economics of mobile apps is probably the reason why I've never bothered to self-publish one: it seems that the effort would be economically impossible for the effort to succeed, such that I would never recoup the time that I could instead be selling to someone else.

It goes like this: "Pay me (tens of thousands of dollars) to write and to debug your cross-platform native app, and I will do it masterfully ... but don't try to offer me 'a piece of your pie' as part of my compensation. And if you'd like to actually get the 'professional-grade cross-platform native app' that that high-schooler promised but couldn't deliver, that will cost money too. But you'll get it, after which it belongs entirely to you." Businesspeople are interested in that. I think it earns their respect that I do ask for money. All of the apps, so far, are internal: only one little thing on a "public" store. But, money earned, and from people for whom the product was a cost of doing their "real" business.

What's been your experience? What niche(s) have you found?

We make a lot of money developing apps.

Part of it is that we develop the embedded devices that the applications are talking too.

I think there are some issues which are if they hire some whiz kid or work needing, individual developer. Or the case where they have it made by an offshore company that has locally based sales.

In the case of a whiz kid or needy individual developer, that person is local, but does not get paid what they should, maybe they even lose money by some interpretation. I.e. say working at their normal level they'd make $10,000/mo, but for some app where they need the work, they may see $5,000, believe they can accomplish that in a week, and be ahead of the curve, and then they find that they have to invest 200+ hours of their time into it. That's what I mean when I say "by some interpretation". Because, while it's true that they made money, they didn't make it at the level they should have.

The offshore company, I don't know. They can undercut and one wonders how long that will last. They are capable of very good quality too. One of the most powerful parts of that is the locally based sales representative. Here in the US we've engaged some who sell out of one of our middle time zones, plus they travel. Ergo, during any given workday, they are available, or they have a secondary contact when they're out of the office. And then that sales person engages the out of country development assets. For serious technical calls where those assets are required, they then have their most senior developers get on a call during local business hours. That works when they have parallel app examples to offer and a very low price. What doesn't always work is adaptation to differing concepts. We got one company to quote, they wrote up what seemed to be a very lengthy offering. This was all the result of our client having a senior person offer up this third party as an alternative where they wished our company to manage that effort and validate the application. We obtained that lengthy quote, it had many examples of apps, but none which matched the desired client's app form. Attempts to obtain a more substantive quote were not successful. We realized that they had a boilerplate quote and then they would just have their persons work tirelessly and iterate with the final client to attain their results. Sort of a high tech version of oneupmanship where the winner was the one who didn't give up in frustration.

Interesting. The "Linux is 1 percent of Steam's market" figure should probably be looked at in this context.

The fact that you manufacture the device is the key point, I think. The app is simply part of the sales process for the device. The same is true of my focus on internal web-sites and likewise apps. People are entirely accustomed to the notion that "a web site is free," therefore that an app should be also.

I offered a "hobbled free demo" of my software product for about one month. Over 8,000 copies (of release 1.0) were downloaded, and many folks started asking for support. Instantly, I realized that if I collected just a few dollars from those people, I could remove all "hobbles" except the time-limit and I would only be dealing with serious customers. "Rental" orders immediately started coming in, and most of them converted. (Whew!)

I downloaded a few ... very few ... apps over the years, and I instantly discovered that the presence of "ads" utterly and completely repelled me. I yanked the apps immediately and posted one-star reviews. It didn't help, so I basically stopped buying apps altogether. Yes, I write them. No, I don't buy them.