He was with girls and had a sweet car.
He didn't act that way UNTIL he was Batman. Before he was Batman he was an angry, college student who wanted to take out Joe Chill. Then he was away for 7 years training. When he came back, he was preparing to be Batman.
Oh, another weird little thing. All of Gotham must be dumb, especially Gordon (even though he makes several claims that he doesn't care about his identity) considering they don't know who Batman is.
In Batman Begins, Bruce Wayne is declared dead after he goes missing for 7 years. He returns and it's a media frenzy, he's all over the news. A few weeks/months later, Batman appears and also attracts the media.
This happens again in TDKR but it is even MORE noticeable. Nobody has seen Bruce Wayne for 8 years. He's a hermit who lives in Wayne Manor and people make up stories about him (much like the '89 Michael Keaton Bruce Wayne). He soon returns, clean shaven and with a cane and attracts media attention. A few days later, Batman returns after being gone for . . . you guessed it 8 years.
Dumb Gothamites.