There's only 93 million PS5's out there and only 34 million XBOX Series consoles out there. Many of the owners may not be interested/passed away/destroyed the console or picking up dust in some basement. You really think with this small userbase Rockstar is gonna be able to sell enough copies of GTA6 to recoup costs let alone make a profit?It's as simple as that.
It's going to recoup costs + make a profit day one. Shit's going to sell 30 million copies and most of those will be the $100 edition