This thread reads like one about a console maker.
Lots and lots of people defending an effective monopoly with nonsense arguments.
"Sell elsewhere if you don't like it" - ...
"30% is standard, everyone takes 30%" - So if everyone took 50% it would be okay? What if they took 70%, 90%? By that logic it's ok as long as everyone does it.
That the big guys don't throw away money by lowering the cut without pressure should be obvious.
30% is more than console manufactures take/took as their physical cut.
30% is more than a retail store gets.
Steam takes 30% - for what?
They take 30% because they have the market power, not because of any service they provide.
I'd suggest you read through the thread. I've already posted about the pointlessness of the statement "Effective monopoly", since it's not an actual term within economics, which this is really what the whole discussion is about. Market Dominance is not anything like a monopoly.
Stump posted what Valve actually do for their 30%. Other storefronts do a lot less, and have less features, and take the same (or almost the same, in the case of Humble).
Retail stores took, at one time (my figures may be outdated) 70% to cover everything, on worse deals for publishers, like sale or return.
Sony and MS take about 30% of every sale, and have restrictions on where you can purchase items.
And as has been pointed out time and time again, if Valve lowered their percentage cut, it would be counted as predatory pricing, and would be literally anti-competitive.