Steam

30% is an absurd cut for a store that has such a monopoly that if you don't release there your game is pretty much cancelled

That's exactly why they take 30%. Because having your game on Steam is a huge deal. Because Steam is very popular and lucrative. Because it's well-made and useful. Little Timmy wants to skip to having a popular and lucrative platform without first doing the step of making it well-made and useful.