Alcohol in sufficient quantity removes inhibitions and people will say and do things they would not normally do. What you heard is probably something he's been thinking about for sometime and just got verbalized. It could be something he has felt perhaps for a long time.
I've always believed that we are more ourselves when drunk - for example I'm exactly the same except I slur my words. But I have friends who become incredibly obnoxious, rude, sad, angry, and just over assholes.
So I tend to trust what I hear when someone's drunk.
Excess amounts of ethanol tend to eat away at a person's inhibitions. People, guys included, become more impulsive. There may be some truth in what an inebriated guy says but I'd take his words with a grain of salt. I wouldn't say a guy means what he says word for word but there is a root cause for what he says.