agree, because "free" can be neither "cheap" nor "expensive"

It's not free at all. If you buy Windows through the official channels it's quite expensive. If you buy it on the grey market, it's dirt cheap, though.

And even if you pay $1,000,000/day to use it, it still spies on you and sells your data to outsiders.

Exactly, yet lots of people are happy to keep using it and paying the price to do so, despite the existence of free and far superior alternatives.