How to Win the OS Game
Microsoft beat Amiga and GEM the same way it did everything else: by persisting longer and moving faster than the competition.
I worked in GEM for years (using Ventura Publisher). It was a nice environment, but basically just a GUI, not an OS. I also spent time with the Amiga. It was a nice OS, if you could get anything done between Guru Meditation Errors. Neither platform evolved much, before eventually fading away.
Windows 1.0 had a horrible UI, but it was well-architected, with features like multitasking, that neither Mac nor GEM could match. With the release of Windows 3.0, five years later, it had evolved into a slick, stable, attractive OS, while still offering a smooth migration path from the dominant platform of the time (DOS). With Windows NT, five years after that, Microsoft left all competition behind in the dust.
Subsequent advances were much smaller. Windows 2000 brought the consumer UI to the Windows NT codebase. Windows XP was 2000 with a gaudier skin. Vista added DRM and transparency effects. Windows 7 fixed the problems of Vista. Windows 8 and 10 were sizable steps backward, adding only 'improvements' that benefited Microsoft, rather than the user. There is absolutely nothing you can do in Windows 10 that you couldn't do just as well in Windows 2000. That's 20 wasted years.
Tragically, Microsoft was a great company only while it had actual competition. The Microsoft of today is a at best a caricature of its former greatness. When companies get to that stage, they never come back. The quicker we dump them, the sooner the digital world can surge forward once again.