What causes someone to be this conceited?

I've known my guy friend for like 10 years we're both in our mid twenties. In high school he was a skinny kid that was always goofy, but sweet. A lot of girls didn't give him the time of day back then, but I was always nice to him. Recently I reconnected with him and has been in the marines for the past 5 years. However, he has changed. Now don't get me wrong my friend is HOT now. He's has a tan complexion (he's hispanic), green eyes, jet black wavy hair, goatee, 3 dimples, 6'1 and has muscular body. Anyway, since we've reconnected I find him to be such an @$$hole. He thinks every woman wants him. He even told me that some women had tried to trap him. When we went out to lunch he would make it his personal business to let me know what females that he thought were attractive. One time he even had the to tell me that a female looked better than me and he was in love with her. I'm not a bad looking woman. A lot of people have told me that I look like the late great singer Aaliyah, but I'm just a lot shorter than her. He once told me that a female fell in love with him just because he took her out to Applebee's. I just rolled my eyes. What really got me was when he told me that this one female fell in love with him after giving him and nothing else. He told me if we ever slept together that I would have to pay him for his services pfftttt. He calls me when he needs to vent and I listen to him, but when I vent to him he totally brushes me off. I haven't talked to him in 3 weeks because I'm sick of his $h!t. I wish he was the same sweet guy I used to know, not a narcissistic prick that he is now.