He has displayed a high competitive spirit for me, and if he has that, he'll be fine. Simple question is if he likes competition more than he likes partying. If work is always gonna be more important than partying he's fine. If not... he's gonna get into trouble.
I have seen people that work and party equally hard. You wouldn't believe such a switch is possible, but for some it is. Problem is, to be among the best, it's 90% work and 10% partying.
It's easy to jump on him, but remember that vacation time is mostly about partying. You don't have to like the women he goes after, the clothes he wears, the music he listens, his taste in jewellery or hairstyles or whatever.