Probably stress. Running a business + a nonprofit + YouTube is already a lot. And on top of that I think he’s recently been diagnosed with being in the spectrum, which is stressful on it’s own way as well. I don’t think he’ll stop though. Dude’s been burning himself like that for over a decade, it’s probably the only way he knows how to live.
I agree, however I think the main cause is studios/publishers just deciding where to allocate the time. Devs are just the ones implementing these shitty decisions.