Good post, and thank you for offering a conversation point versus an attack.
Obviously from the outside looking in, he doesn't seem depressive. He seems like he has what he wants. But he is obviously stating that the material success isn't fulfilling to him. He grew up trash poor, so he doesn't need "things" and he seems his happiest when he is training with his brothers, building them up and building himself up through physical tests.
But we can see that as he's become more popular he is spending more time online, engaging in the bs culture of today, talking to influencers and doing other shit that doesn't really seem to fit him.
Some people are meant for more, and some aren't. He seems like the kind of guy who won't finish his story at UFC champ and online loudmouth and maybe his current dissatisfaction is reflecting a subconscious awareness of that. But it remains to be seen.
Also, and seriously, he gets punched in the head a lot and has voiced concern about the toll the beatings will take on him, which could be a factor.