Linus Torvalds recently did an interview [0], where he talked about, amongst other things, just how hard it is to get an OS off the ground.

Excerpt: “I used to think that some radical new and exciting OS would come around and supplant Linux some day (hey, back in 1994 I probably still thought that maybe Hurd would do it!), but it's not just that we've been doing this for a long time and are still doing very well, I've also come to realize that making a new operating system is just way harder than I ever thought. It really takes a lot of effort by a lot of people, and the strength of Linux—and open source in general, of course—is very much that you can build on top of the effort of all those other people.

So unless there is some absolutely enormous shift in the computing landscape, I think Linux will be doing quite well another quarter century from now.”

0: https://www.linuxjournal.com/content/25-years-later-intervie...