They sell fine. Look at BG3.
What they don’t do is make money hand over fist without the need to design more product, as happens with subscription-based, game-as-a-service multiplayer titles. Some companies don’t want to make good games. They just want to make good money.
More expensive and less profit
Like the other person pointed out with GaaS you don’t even need to finish the game before you start making money
However BG3 had a big already established IP and successful Divinity games beforehand
I will give you some advice that I was given “you need a hit before you can have a hit”