Every company in a soft monopoly charges the industry standard, that is how soft monopolies work.

They all stop charging what it's worth and pick a number together that equals maximum profits.

No, they wouldn't.

Anti-trust law exists to prevent companies from overcharging consumers, something they can do when they don't have competition.

Valve keeping their prices far higher than costs is something that can open them up to anti-trust scrutiny. Competitively lowering their prices while still maintaining profitability cannot, as that is the exact goal of anti-trust laws in the first place.

It's also fucking wild that gamers hate Tim Sweeney so much. What has he used his fortune to do? Build a reasonably priced and powerful third party game engine that makes it easy for indie developers to build games, spent hundreds of millions of dollars trying to break up Apple and Google's walled garden 30% bullshit, launched a PC store to try and do the same with Steam, and bought tens of thousands of acres of US land to preserve for nature conservation. Oh what a moustache twirling monster!