They could, but why would they when 30% is fair still? You are not entitled to setting other people's asking price, and they are entitled to setting the cost of their own labour.

If anyone is greedy here it's you, demanding to have a say in how much is a fair rate for someone else's time and skill.

You stated your opinion as a fact, and qualified it by saying you're a game dev.
Back up that claim. Shouldn't be hard to do.

valve and steam are not the friendly aw shucks corporation they’ve been whitewashed into.

And the goalposts go flying.

Who the fuck cares if valve is cute and cuddly? Who even wants that in a marketplace other than morons who think they can take advantage of someone else's kindness?

Valve is a company, their job is to make money for the people who own it.

• You the customer want the most out of your transaction with them, they know it make it a priority.
• They understand that devs working there making fucktons of money is good because they'll stay and be motivated to work, so they are selective on who they hire and then pay them an insane amount.
• They want to avoid microsoft cutting their nuts off so they pushed linux as a viable alternative.
• They want devs to sell on their platform so they refined a business deal that works well enough that they get several new games on their storefront a day and still make back their operating costs, despite servers that can literally be used to benchmark several gigabit download connections.
• They are the most economically effective company in the world and they achieved it by not enshittifying their platform and not going public.

Selflessness would literally be a downgrade, I want Valve to have every damn cent they earned.

They're not the only game in town, they are the best game in town, and at every turn they make an effort not to become a monopoly, either, because they know the good will of their customer base is more important than attempts at short term spikes in company revenue, which is only possible because they are a privately held company.

So yeah, are they cuddly and nice? No, fuck no, but they are extremely effective while providing a service that puts every other provider in their field to shame, so why the fuck would I want them to change?