Is 30% on average "huge" considering the platform and total number of averages monthly users? I know that number does move around a bit as well.

I guess considering the ease of use for users and the fact that other platforms exist, they might be considered a monopoly only because nothing else of quality has shown up. It's not like they're buying out competitors and paying politicians to create laws and expectations to give them a competitive advantage. They're literally just better than the other shit. Except arguably GoG which is solid in its own right, though not in the same ways as Steam.