Can i please change myself?

I am a 17yr old guy in high school (rising senior) and I have just become quite self-conscious of myself in regard to girls. They (girls) tell me that I am actually a "thoughtful,loving, and caring guy" even though I see the stuff that I do for as anything any friend would do. What I have just realized in my head though is that to any girl, I am basically a tool. I can cheer them up, give them good advice, care for them and listen to their problems but there would be the catch. I am not handsome, I am not wealthy, and I don't have the most masculine build ( size of muscles, height, manhood), so how in the world would I be the preferred guy for ANY girl. In my school, I observe quite a correlation with girls liking guys that I know are total a*******. They don't treat any girl with respect or kindness, but they seem to get all the girls. Compared to their looks,wealth, and masculinity; I am pretty sure my "caring, thoughtful, loving" attitude is insignificant to the female gender. The problem is that I really like one of my best girl friends and I admit that I don't have the courage or "" to approach her about it. The common mantra in my head whenever i talk to her is" She could go for all those good-looking, rich jerks .. Why would she ever choose you?" In my own opinion and feeling, I think she is the greatest girl in the world, and the most beautiful. I had enough courage to tell her that much and she said " I don't think so.. You are the only one to ever say that to me." We are friends, and it really pains me to think she would shun me for the jerks in the school. Consequently, I lost confidence in myself and honestly think I am worthless because of it. I know that its not an "appealing" thing for woman, but I just can't fake confidence. My best friend(basically my brother) threatened to beat the s*** out of me for thinking like this and tried cheering me up to no avail. Finally, he said " They get what they want because they have dude" and my only response was " F you". (we just started speaking for the 1st time in 2 wks yesterday). To me it only seems that all girls want a rich, handsome, smooth jerk to treat her like s***. I am thinking about becoming like that ( at least the jerk part) as it seems like my only hope. Naturally, this is hard for me to do because I am so used to being the "nice guy" and i am conflicted about doing so. Should i change who i am?