I suppose I can technically answer this. I do use Linux full-time now and have for several years, but prior to that I had a few false starts where I’d switch back to Windows. Usually it was because I’d encounter some technical issue I just didn’t know how to fix besides reinstalling the whole OS, or a graphics driver issue. For example, at one point when I had an NVIDIA graphics card only the newest drivers from NVIDIA’s website supported it but the ‘stable’ drivers in Ubuntu’s repo didn’t, so I had to manually install the drivers. Except then whenever the kernel was updated by Ubuntu (basically every week) my display stopped working and I’d have to switch into a TTY and manually reinstall the drivers.
Now I know how I’d fix that (setup some rule to reinstall the drivers whenever the kernel updates, which I believe is now the default anyway), or use a PPA containing the latest NVIDIA drivers, or use AMD instead - but really any kind of problem that requires the user to both diagnose and fix the issue prevents non-technical people from adopting it.
Those who tried Linux and went back to Windows, what caused you to go back to Windows?
Additionally, what changes are necessary for you to be able to use Linux full time?