I realized on my own that backing up to some cloud such as Google's or Amazon's was not the best idea, even before I became anti-Google and anti_Amazon; but I note that Protonmail, which I use daily, offers a cloud drive with its paid subscription. (Or will offer--I think it was in beta last time I saw the subscription offer.) I'm happy backing up physically anyway, but if I wanted to use a cloud, would Protonmail's cloud be a safe choice? Or only less unsafe?

I've thought about subscribing anyway, so I can make as many folders as I want. So, I suppose the question might be phrased as: if I subscribed, should I use the cloud?

Really up to you. I am a big cloud user but in my case it’s iCloud. I do not keep anything sensitive and if I do, it’s in an encrypted container. I also back up locally. Some people dismiss cloud but I have literally had data in iCloud for over a decade with zero loss. I am a paying customer because I feel if I am paying, I get more support and feel the provider is less likely to just drop the service. I don’t back up operating systems to a cloud because I don care about them, only data. OS installs are easy so I don’t worry about that.

Sure, I could set up a local server or use my NAS as a “cloud” but I hate opening firewall ports and allowing inbound connections. I like a simple network and have zero desire to maintain a server. That’s just my preference; many people do host local servers on their LAN but that is their preference.

I never feel a need to back up my Linux OS either, for the same reason. It installs so fast (much faster than Windows XP, the last Windows I used) that I see no point. I reinstall from my liveUSB; briefly apt-get upgrade; then apt-get install a copy-and-pasted list of the applications I need to reinstall; and I am up and running again.

The bigger a provider is, the more investment they'll have in security (hopefully). But they'll also be a bigger target. And no matter what the privacy statement says, can you be 100% sure they're not spying your data? I can't.

I have some cloud storage, but never keep anything there that could hurt me if I got hacked. All my important stuff is kept local, on multiple rotated backups. Only thing I'm missing is offsite storage, which I could remedy by keeping a backup at a trusted family or friend's house.