People have been using Linux as a desktop for a long time now. The problem is that you can not buy it pre-installed. Sure, somewhere here and there you can, but not that big a choice.
People buying Android and there is no issue there, so it is possible.
Have it pre-installed and people will use whatever is available.
For the average user, a Linux desktop is good enough. Email, web and that is about it. Next are the gamers who will need Windows for their games.
Companies will have written code specifically for Windows, so they do not want to switch yet. If it weer up to them, they would still use Win95.
So have it pre-installed and people will use it. MS knows this and their customers are not the end-user. They sell to Dell.
The reason that there is no price difference, is because companies pay Dell and others to have their shareware installed. The cost for Windows is payed for by Norton and the others that are on your PC already. Without that income, the price would be higher and Linux would be a viable option for them.
And again: yes you can buy a PC with Linux installed if you look for it. Walk into a store and look how many of thm are Linux.