Re: They tried to cheat their way out of payment system they knew upfront about.
"Apple's end of the so called in-app "purchases" is, in reality, and in practice, offering nothing more than a payment system/broker,"
You just swallowed Epic's self serving propaganda. There's a lot more than a payment system / broker. If you look just at payments, Apple handles all the taxes for about 150 different countries. That's worth a lot. At the end Apple hands you the cash, and all taxes (VAT in all kinds of countries) have been taken care off. Your credit card company doesn't do that.
Next, Apple does indeed run the App Store, which costs money.
Apple makes in app purchases _secure_. You can be sure that there are no forged in-app purchases, where the developer doesn't receive any money at all.
Apple provides lots of services to the developer, like push notifications, secure login with the user's AppleID (which is broken for Fortnite right now), maps, iCloud storage etc. etc.
And finally, Apple takes the same percentage from everybody. Including from free apps. So companies like Fortnite contribute by financing the same services for free apps, for apps from small developers, and so on. If Apple gave in to the real big money makers and reduced the percentage for them, they would have to increase the percentage for all the little ones.
Being one of the little ones, I'm all for a Chinese owned company to help paying for my app to get on the App Store.