You say they engage in monopolistic practices, but did you cite one? You dismissed a lot of the same points from the video that I did, but I don't see what supports your point that they're behaving as a monopolist.

not to mention you have the entire steam proton system and the VR system at your disposal both of which are Super complicated to set up stand alone.

Proton is actually super easy for a competitor to set up standalone. There's nothing stopping the likes of GOG from just distributing Proton or Wine with their Windows executables for Linux customers, if they wanted, and they can even obfuscate it and make it invisible to the player like Steam does. The big trick that Valve pulled out of their hat for Proton, which again is not monopolistic, is that they re-encode videos that use Microsoft's proprietary video codecs, since they can't legally share the DLL that enables playback of those videos. To do what Valve does here is replicable, but it comes at a cost to the distributor. I can't speak to the effort involved in setting up a competing VR platform, but it seems to be of less and less concern at this point.