On the other hand, when it comes to WinRAR, the majority of people use it not because of its unique features (like the RAR format) but because it's considered the mainstream archiving software and they don't know any better.

WinRAR isn't losing much sales because it's easy to use without paying; if it was harder to use without a license, people would simply use alternatives such as 7-Zip and it would become the mainstream archiving software and WinRAR wouldn't have the brand awareness they have now. I'm assuming RarLab knows this because otherwise they would've patched the loophole long ago.