I think this is slowly changing. I'm seeing more and more people who have given up Windows and moved to 1) Macbooks, 2) tables, 3) Chromebooks, or 4) just using phones.
I agree that the Linux desktop failures aren't the primary reason people run Windows, but it hasn't helped.
>It would probably end up cheaper, since the cost of development of a well made, bugless Linux desktop would probably amortize to less than the Windows tax per unit.
There's no "probably" about it. We already have fairly decent Linux desktops (just use Ubuntu: for most people, it "just works" most of the time, and it costs nothing). The Windows tax is already the largest BOM item for a PC. The additional cost needed to make Debian or Ubuntu into something even more bug-free and fully-featured wouldn't be that much. In fact, this was basically the whole idea behind many Linux distros: give them away for free to the masses, but sell support contracts to large corporations and governments to finance it. Unfortunately, that didn't work out so well. It's worked for Red Hat, but that's about the only company that's done well in this space, mainly because of US Government contracts.
Linux desktop really sucks.
While I am as idiosyncratic as anyone about Linux desktops (I run the Trinity Desktop Environment, which is basically the old KDE 3 kept up to date), and I am no fan of systemd or hw support problems (amdgpu, for instance, insists on locking up my laptop every so often), I don't think any of these things are the primary reason people run windows. I think the primary reason people run windows is that they have to use it at work and so they're familiar with it and don't even bother considering other alternatives.
> Instead of whole community stepping together and make ONE well made, bugless desktop
The reason this hasn't happened is simple: there are no market forces driving it to happen. What would create such market forces would be for large corporations, or governments, to abandon Windows for Linux. It would probably end up cheaper, since the cost of development of a well made, bugless Linux desktop would probably amortize to less than the Windows tax per unit. But it would require someone to be willing to do something different from what everyone else is doing, and that's not a way to get ahead in a large corporation or government.