Wanting GT for PC is PRECISELY why GT is not on PC.
GT, and several other PS5 exclusives, exist to sell the PS5. Sales of PS5 mean more people buying games for the PS5, and for every PS5 game sold, Sony gets paid a fee.
Releasing exclusives for the PC is exactly what has killed the Xbox. They chased per unit profitability, and destroyed the overall profitability. Sony has experimented with it for a few titles, but this won't continue. GT would be literally the last title to every go to PC because it is the most used title to attract people to Sony televisions (and Sony surround systems, etc).
Sony is an electronics company first, and then a content company, and they'd much prefer that their content be used on their electronics.
It's akin to asking why Google doesn't make an iPhone