Yes, unless you build everything from the game engine to the distribution channel yourself, there is a cost to doing business. IIRC Epic Games Store offers a more reasonable 88%/12% revenue split, while Steam uses the same rapacious split as Apple and GOG at 70%/30%.

However, Steam offers more eyeballs, and in particular, more eyeballs that actually buy games.

The extra 18% doesn't feel as unreasonable when you get to make a lot more sales.

Cool, that's why godot and open source are much more reasonable paths moving forward.