It would also be very hard to compete with products that are this mature. Linux, Windows, and macOS have been under development for a long time, with a lot of people. If you create a new OS, people will inevitably compare your new immature product with those mature products. If you had the same resources and time, then maybe your new OS would beat them, but you don’t. So at launch you will have less optimizations, features, security audits, compatibility, etc., and few people would actually consider using your OS.
It would also be very hard to compete with products that are this mature. Linux, Windows, and macOS have been under development for a long time, with a lot of people. If you create a new OS, people will inevitably compare your new immature product with those mature products. If you had the same resources and time, then maybe your new OS would beat them, but you don’t. So at launch you will have less optimizations, features, security audits, compatibility, etc., and few people would actually consider using your OS.
And the new OS wouldn’t have a lot of software. Microsoft tried to make a mobile W10, but software availability was a serious bottleneck.