Here, you can see offices and school laboratory who still use Windows 7. Because they said it's the most stable version of windows 7. I think there are still much need improvements on windows 10. Tho for me windows 10 UI is far much better than windows 7. But people who still use W7, I don't think there is something wrong with them.
The problem with Windows 10's stability is that it's too unpredictable.
Instead of having 1 major release every few years, Windows 10 gets 2 big updates per year, which are also very poorly tested most of the time.
I actually disagree with Windows 10 UI, it's the most inconsistent UI system I've ever seen on a commercial OS.
There's the Win32 UI for all Windows 7 and earlier apps, Metro UI for all Windows 8 apps, Modern UI for all Windows 8.1 apps, UWP UI for all old Windows 10 apps, and Fluent UI for all new Windows 10 apps.
Each UI works differently, resulting in some apps having a menu bar beneath the title bar, some having on the top of the window, some having hidden inside a hamburger menu on the left, some requiring to pull one from the right, and some having it as part of the title bar.
And some apps use all lowercase, and some using a capitalised letter at the first word.
Windows 10 even comes with 2 completely different control panel apps (classic and modern), and neither has all configurations in 1 place, so you must use both in order to configure everything.