Many people already have a laptop and want to build a PC specifically for gaming, though. Upgrading isn’t all it’s cracked up to be IMO, it’s definitely nice to have but a console lasts the entire console generation (5 years give or take?) if you ignore then mid-gen upgrade which is usually entirely optional.
My pc lasted over 10 years without a GPU or CPU upgrade. Now it doesn’t keep up with AAA titles but there are still plenty of games, old and new, that I can play.
What would make you think that a PC wouldn’t also be able to do this for longer? Lol.
Maybe this is a local popularity thing or in your immediate sphere, but most people i know dont have a laptop, in fact its actually quite rare. The people i know only have a laptop if its a work device and otherwise either have a PC for gaming/hobbies or just use a phone/tablet for their needs