...But the main problem is that many regular Win-users won't feel like they will gain anything in terms of actual functionality but still have to invest time and energy into the migration. If MS wouldn't erode personal freedom and privacy more and more, people wouldn't see much need for a change.
It's like being forced to move out of a comfortable apartment after decades because the new landlord started to read your mail and sneak into your apartment...
Exactly. Changing from Windows to Linux will be a difficult task for many people (even the drive designations are different, which will be a big problem for some people), and for others it won't so much be difficult as pointless as you're learning to use one OS (Linx) when you can already use a different OS (Windows) to the level that you like/need. Even today, many, many people just want to be able to use their PC (or laptop, or tablet, or phone, etc) with as little effort and potential confusion as possible, and they don't care in the slightest what the OS is, or it works, as long as it runs the programs and games that they want to use.
If Windows 10 could be used for the rest of my life (two, maybe three decades, probably), then I would stick with Win 10, and I don't doubt that the majority of PC users would say the same. People tend not to like change unless the change brings noticeable and existent improvements and benefits. Which Windows seldom does. I don't want Co-Pilot, or Recall, or anything else that MS is currently promising (that I know of).