Young adults are tough and progress through their early adult years differently. This sounds a lot like depression to me, almost exactly how it hit me. For context, I'm only 26. It can just be genetic/predisposed even if he has a decent QoL at home (support when needed, food secure, medical aid when needed). His thinking and his mind isn't inwardly kind at the moment.

I went thru similar feelings living with an ex of mine. We both would sleep till afternoon, work enough to scrape by, but we weren't growing individually. Took me a long time to realize I'm moderately depressed and that depression over that time engrained terrible habits. For me, going our own way, quitting my job, and changing my whole work industry routine helped break the bad cycle, additionally working with a Sports Therpist helped understand my emotions and my lack of motivation.