Linux

1. False promises early on

We desktop Linux users are partly to blame for this. In ~1998 there was massive hype and media attention towards Linux being this viable alternative to Windows on the desktop. A lot of magazines and websites claimed that. Well, in 1998 I can safely say that Linux could be seen as an alternative, but not a mainstream compatible one. 25 years later, it's much easier to argue that it is, because it truly is easy to use nowadays, but back then, it certainly wasn't yet. The sad thing is, that we Linux users kind of caused a lot of people to think negatively about desktop Linux, just because we tried pushing them towards it too early on. A common problem in tech I think, where tech which isn't quite ready yet is being hyped as ready. Which leads to the second point:

2. FUD / lack of information / lack of access to good, up to date information

People see low adoption rates, hear about "problems" or think it's a "toy for nerds", or still have an outdated view on desktop Linux. These things stick, and probably also cause people to think "oh yeah I've heard about that, it's probably nothing for me"

3. Preinstallations / OEM partnerships

MS has a huge advantage here, and a lot of the like really casual ordinary users out there will just use whatever comes preinstalled on their devices, which is in almost 100% of all cases Windows.

4. Schools / education

They still sometimes or even often(?) teach MS product usage, to "better prepare the students for their later work life where they almost certainly use 'industry standard' software like MS Office". This gets them used to the combo MS Windows+Office at an early age. A massive problem, and a huge failure of the education system to not be neutral in that regard.

5. Hardware and software devs ALWAYS ensure that their stuff is compatible with Windows due to its market share, but don't often ensure this for Linux, and whether 3rd party drivers are 100% feature complete or even working at all, is not sure

So you still need to be a bit careful about what you use (hardware & software) on Linux, while for Windows it's pretty much "turn your brain off, pick anything, it'll work". Just a problem of adoption rate though, as Linux grew, its compatibility grew as well, so this problem decreased by a lot already, but of course until everything will also automatically work on Linux, and until most devs will port their stuff to Linux as well as Windows and OS X, it will still need even more market share for desktop Linux. Since this is a known chicken-egg-effect (Linux has low adoption because software isn't available, but for software to become available, Linux marketshare needs to grow), we need to do it anyway, just to get out of that "dilemma". Just like Valve did when they said one day "ok f*ck this, we might have problems for our main business model when Microsoft becomes a direct competitor to Steam, so we must push towards neutral technologies, which is Linux". And then they did, and it worked out well for them, and the Linux community as a whole benefited from this due to having more choice now on which platforms their stuff can run. Even if we're talking about a proprietary application here, it's still a big milestone when you can run so many more applications/games suddenly on Linux, than before, and it drives adoption rates higher as well. So there you have a company who just did it, despite market share dictating that they shouldn't have done that. More companies need to follow, because that will also automatically increase desktop Linux marketshare, and this is all inter-connected. More marketshare, more devs, more compatibility, more apps available, and so on. Just start doing it, goddamnit. Staying on Windows means supporting the status quo and not helping to make any positive progress.

6. Either the general public needs to become more familiar with CLI usage (I'd prefer that), or Linux desktop applications need to become more feature-complete so that almost everything a regular user needs can be done via GUI as well

This is still not the case yet, but it's gotten better. Generally speaking: If you're afraid of the CLI, Linux is not something for you probably. But you shouldn't be afraid of it. You also aren't afraid of chat prompts. Most commands are easy to understand.

7. The amount of choice the user is confronted with (multiple distros, desktop environments, and so on) can lead to option paralysis

So people think they either have to research each option (extra effort required), or are likely to "choose wrong", and then don't choose at all. This is just an education issue though. People need to realize that this choice isn't bad, but actually good, and a consequence of an open environment where multiple projects "compete" for the same spot. Often, there are only a few viable options anyway. So it's not like you have to check out a lot. But we have to make sure that potential new users know which options are a great starting point for them, and not have them get lost in researching some niche distros/projects which they shouldn't start out with generally.

8. "Convenience is a drug"

Which means a lot of people, even smart ones, will not care about any negatives as long as the stuff they're using works without any perceived user-relevant issues. Which means: they'll continue to use Windows even after it comes bundled with spyware, because they value the stuff "working" more than things like user control/agency, privacy, security and other more abstract things. This is problematic, because they position themselves in an absolute dependency where they can't get out of anymore and where all sorts of data about their work, private life, behavior, and so on is being leaked to external 3rd parties. This also presents a high barrier of convincing them to start becoming more technically independent: why should they make an effort to switch away from something that works in their eyes? This is a huge problem. It's the same with Twitter/X or Reddit, not enough people switch away from those, even though it's easy to do nowadays. Even after so much negative press lately most still stick around. It's so hard to get the general population moving to something better once they've kind of stuck with one thing already. But thankfully, at least on Windows, the process of "enshittification" (forced spyware, bloatware, adware, cloud integrations, MS accounts) continues at a fast pace, which means many users won't need to be convinced to use Linux, but rather they will at some point be annoyed by Windows/Microsoft itself. Linux becoming easier to use and Windows becoming more annoying and user-hostile at the same time will thankfully accelerate the "organic" Linux growth process, but it'll still take a couple of years.

9. "Peer pressure" / feeling of being left alone

As a desktop Linux user, chances are high that you're an "outsider" among your peers who probably use Windows. Not everyone can feel comfortable in such a role over a longer period of time. Just a matter of market share, again, but still can pose a psychological issue maybe in some cases. Or it can lead to peer pressure, like when some Windows game or something isn't working fully for the Linux guy, that there will be peer pressure to move to Windows just to get that one working. As one example.

10. Following the hype of new software releases and thinking that you always need the most features or that you need the "industry standard" when you don't really need it.

A lot of users probably prefer something like MS Office with its massive feature set and "industry standard" label over the libre/free office suites. Because something that has less features could be interpreted as being worse. But here it's important to educate such users that it really only matters whether all features they NEED are present. And if so, it wouldn't matter for them which they use. MS Office for example has a multi-year lead in development (it was already dominating the office suite market world-wide when Linux was still being born so to say) so of course it has more features accumulated over this long time, but most users actually don't need them. Sure, everyone uses a different subset of features, but it's at least likely that the libre office suites contain everything most users need. So it's just about getting used to them. Which is also hard, to make a switch, to change your workflows, etc., so it would be better if MS Office could work on Linux so that people could at least be able to continue to use that even though it's not recommended to do so (proprietary, spyware, MS cloud integrations). But since I'm all for having more options, it would at least be better in general for it to be available as well. But until that happens, we need to tell potential new users that they probably can also live with the alternatives just fine.