I, too, am very competitive when I was young. I think that's because being able to surpass others provides validation and recognition that I am actually doing something right. And with that comes this feeling of satisfaction because I made my parents proud, and other people started to notice me or like me.
But I as grew older, that sense of competitiveness has slowly disappear. I think I have come to realize that being on top won't really make me happy. But that doesn't mean that I'm settling on being average. Rather, I'm more inclined into my personal growth, and just be in competition with myself and not with other people. For me, it's like saying, I aspire to be better everyday rather that being better than someone else.