Being an entirely private company makes that much less likely, especially with every other employee heavily invested in the way that valve operates now.

I have to hope that if someone is in a position to ruin the company, they can see how much of a money-printing machine it currently is and not mess with their golden goose. I think the first sign of enshittification would be if they started selling ad space for games. (rather than doing an algorithmic discovery-queue, and promoting sales like they currently do)