Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
Operating Systems tend to live and die by the dedication of their users.
People, like you and me, grow accustomed to using computers in a particular way. How our file system is laid out, what the desktop looks like, what applications we use to get work done - over time we become used to every nuance of our systems.
When that system changes dramatically, we start thinking “hey, this annoys me... I wonder if the grass is greener over in that pasture over there.”
Windows 8 is a great example of this. As Microsoft changed the core user experience, folks (at least some folks) began to look elsewhere. Or when Apple first released MacOS X 10.0 and changed just about everything about MacOS (new apps, new look and feel, new file system layout, broken backwards compatibility). At that moment, many Mac users considered jumping ship.
This same phenomenon applies to Linux desktops as well, which is perhaps a bit counter to common thinking – many use Linux because of how astoundingly customizable it is compared to most other Operating Systems. But it applies, just the same.