At least the Epic Games Store is raking in heaps of cash. Tim Sweeney must be thrilled he divested so much into taking on Valve. Certainly, nobody in or outside the industry could have seen that not working out. It is a bold strategy to burn billions just to prove you are the smartest guy in a room that is currently being cleared for layoffs.
I think It is unlikely EGS cost billions of dollars.
Costing a single billion dollars in dev time would be 1,000 developers working 5 years at 200k/yr/ea.
Modern CDNs and Cloud providers have made hosting files incredibly cheap. It isn't 2005 any more, digital delivery is largely a solved problem. I've been on projects that stood up basic digital delivery mechanisms in days to weeks for hundreds to single digit thousand dollars for much smaller scale. Given the slow pace of development its pretty clear it has a small team. I wouldn't be surprised if its at breakeven or near breakeven.
The UI/UX for that is an unsolved problem for it though.
I would rather a billionaire try and crack a few monopolies than play Hank Scorpio or enter the mega yacht dick measuring contest. I never quite understand the vitriol that gets summoned whenever someone tries to take on Valve.
But, having actually played their games recently I've been exposed to their abject greed more than most people. They're ground zero for everything people hate in the industry, but somehow they've avoided all the blow back. I think one day we'll get a good breakdown of all the shit they've pulled, particularly with gambling and esports and people will see Valve in a new light. You don't pay people leaving the company 6 figure "bonuses" for signing an NDA if you don't have shit to hide.