There's something he said in that interview that felt like a hint about why he's behaving like he doesn't give a damn anymore.
"For a while there I was like really getting demotivated and losing sleep over the sort of the threat of AI danger and then I finally sort of became fatalistic about it and said well even if I knew annihilation was certain would I choose to be alive at that time or not and I said I probably would have choose to be alive at that time because it's the most interesting thing. Even if there was nothing I could do about it. So then, you know, then basically sort of a fatalistic resignation help me sleep at night because I was having trouble sleeping at night because of AI danger."
A billionaire who believes that we're all probably doomed within the next decade and has accepted it so he can sleep at night.
Maybe explains a lot about his behaviour? If you know this all ends in the next few years, why not just try crazy shit.