How can she like him and not me?

Now this might seem a little arrogant, but it regards a girl I absolutely adore so I don't care how I come off in this question. This girl is almost exactly like me in every way; we go to the same concerts, watch the same movies, like and hate the same people, etc. etc. We even finish each other's sentences. Every time we hang out, we have lots of fun and share lots of laughs. She tells me that she appreciates all the stuff that I do for her, and she has no idea what her life would be like without me. She has even admitted that she would be the happiest woman in the world dating me if only she liked me that way. The problem is that the guy she likes that way is way worse than I am in almost every area of life. I am smarter (but hes pretty smart too), funnier (this guy just kills jokes, more fit (I have six pack abs, he has a beer belly and weighs 250 pounds), more attractive (girls don't lick their lips at me but this dude is just ugly so there's no way he's better looking than me), more liked (shes his only friend), more romantic (as said by most of my previous girlfriends, he's never had a girlfriend), more fun (he's all into politics and boring things, she hates those things), more mannered (he picks his nose in public, scratches his , etc), nicer (I tell her every day how much she means to me and when I see her I always say how nice she looks, he has yet to say anything nice to her), and more confident (I can talk to people; he never socializes with anyone) I have done almost everything for her to see me as more than a friend; I doubled the amount I work out a year ago just for this reason. I compliment her and flirt subtly (she responds positively) while still being a close friend. I've known her longer than him. I get along with her friends unlike him. I give her gifts on her birthday unlike him. I listen to her when she needs someone to talk to, unlike him. I take her out to enjoy new things, and soak up the sun (we're really outdoorsy, he plays WoW all day). I try to make her feel beautiful and loved and cared about every day. I still maintain a life while doing this too; he doesn't. I do all this for her, and he does nothing for her. She even tells me how much she wishes he would say the things I do to her. I have always talked to her about how great of a couple we would be and she agrees, but she likes this guy way more than me. What more can I do? I don't want to lose her; especially not to a lazy, selfish, boring, fat slob like him. Is there any reason she could like him more than me? Please help me figure this out.