I think this relates to Diane’s “I don’t really believe people have a ‘deep down’” speech. He is exactly what you described, a goofball who’s good at making corny puns and is occasionally very incisive about how people relate to each other. He’s not self centered exactly, but he does whatever is going to make him happy, and avoids over thinking things. He likes positive attention so he comes off as a lot nicer and considerate than Bojack does. That’s his whole friction with Dianne, that the things he does for her aren’t really for her, they are to keep her attention on him, and that makes him incapable of really nurturing other people. I think that’s why he’s so desperate to be friends with BoJack, why he’s the one who picks him up from jail to go to the wedding. He see’s how similar they are in that regard.
He’s not smart, he’s clever. He’s just a mechanism that happens to extremely well suited for his environment. He doesn’t have to be introspective, there isn’t a secret plan or calculations about appearing dim to put people at ease. He just does what feels right and it works out for him, kinda. Like his whole relationship with Todd, they spend a ton of screen time together but they aren’t really friends in any meaningful way, hell their is an explicit joke that their relationship is just "Yes, and"ing each other.
Man even the V neck vs crew neck discussion fits with this. It’s not a big deal to him because he’s worried about his visual portrayal, it’s important to him because he likes things that are comfortable, he finds V necks comfortable, so his character should be wearing a V neck in the movie. Simple as.
I had difficulty with this scene on my first watch, and still do, but I think I get it a little more today than when the episode aired.
Others have said he seems to have some kinda non-specific eastern philosophy going on, but I think it’s specific. He’s a Taoist. Taoist don’t necessarily believe in asceticism, him enjoying his accumulated wealth isn’t contradictory. And he says something that’s lifted pretty straight out of the philosophy. Taoist say “if a man tells you he can teach you the Tao, he does not know it.” When Dianne ask if he doesn’t think what he’s doing is a little selfish, he says “I don’t know what to tell you.” Before giving his speech about finding peace. He’s acknowledging his words will have little, if any, value to the listeners, and he never claims to be enlightened, just happy.
Taoism isn’t a selfish philosophy but it is inherently self centered, and more proactive than most eastern philosophies. There is an element of acceptance, but you also should change everything you can that’s making you unhappy, even when it’s a hard choice.
We can (and I am tempted to) disregard cuddlywhisker’s advice as privileged, he has not only money but a lifetime of accomplishment to look back on. But Dianne eventually takes it, and realizes there is no point to trying to do good if it makes you unhappy.
To take it to a much less privileged place, I heard an interview the other day with a chip manufacturing technician in china. A lot of these people are migrant workers, the company will provide you sleeping quarters so it makes more sense to just have your family stay in an area with a lower cost of living while you send money home. He was the most unhappy sounding person I have ever heard. He only got to go home once a year, his wife resented how lonely her life was, and his 4 year old son refused to call him father, because that’s what he called his uncle who helped look after him. Yeah he can’t just retire, but he could say “fuck it” to everything about his current life, and he would probably be happier. Even after hearing the interview, a lot of people would say that would be an incredibly selfish thing to do. Certainly people who know him in real life would say so, the same ones who tell him he’s admirable for doing it in the first place. But I personally wouldn’t judge him in the least. And the hard part wouldn’t be walking away, the hard part would be accepting how it will change how others view him, and still managing to find something that made him happier afterwards. Maybe start over somewhere new, start a new family with someone who wouldn’t demand so much self sacrifice, or simply enjoy the company of those around him and find fulfillment in that.
Taoism isn’t ABOUT walking away from you’re responsibilities, but if it’s a part of it for you than you have to take that leap. Cuddlywhiskers has a short path to happiness available to him, he takes it, and refuses to feel bad about it. If I met the guy in real life I would probably think he’s kind of a smug asshat. But the thing is he wouldn’t care. That’s a hard place to get to for anyone.