It's all about installation.. most folks just can't be bothered to install a different OS then the one their laptop came with. I liken it to the small community of people who tune their cars vs most of the the people who use cars.. just use what they get when they buy.

There is the fact that gaming is a faff with Linux vs something like Microsoft.

It's amazing.. I am a Linux fanboy.. but it's just not a mainstream platform.. and I don't think it will ever be.. and that's OK!