Because he is supposed to be terrifyingly scary, extremely dangerous, one whom we should stay away from, never to befriend to, especially not the one to fall in love with. He is more than capable of putting us to death, starve for our blood every single day and night. Just not supposed to be the one we should go for. Be with him and you risk your life in his hand.
Yes, I used to fell for guys who were cold, insensitive, super-egoistic, full of arguments and always think that he is the best. The kind of guys that girls
would want to should avoid. The kind that girls will hate. I did hate these kind of guys, yet I (used to) liked them a lot. The more I hate them, the more I liked them. How torturing! Be with him, and you risk your fragile little heart in his hand.
I guess this risky kind of things was the one that made me like Edward. Moreover, despite of his vampire attitude, he still have a little humanity inside him. That's what made me like him more.
I just cant wait to finish reading the books.