I don't know if this is true but I don't see why it would be absurd. The man is pretty much an absolute gaming and coding legend and from what I've read about him, he's genuinely interested about code and tech so if that's true I find that actually pretty awesome.

Absurd would be if he had to just stick to management and bureaucracy just because he has a few billions on his bank account. You do you Tim!

Source? 80% of such a massive codebase seems like a stretch. Ue3 alone had over 3 million lines

That's awesome. Lead from the front. He does it becomes he loves it and knows what he is doing. I really admire those kinds of leaders.

I doubt that's true now, but it could've been something like that when UE4 released. The story went that he'd started work on it almost a decade before the release of the engine.