He's tired from fighting for your right to actually own what you buy (as in being able to repair and modify). Which is important in this era of manufactured waste.
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.