First of all, I view Michael Vick as a underachieving quarterback with an attitude. Not a good combination. This is no longer important.
If he is found guilty for doing unspeakable things to animals, he should go face the music. Getting kicked out of the NFL should be the least of his problems.
The "why" is no longer relevant. Maybe he is just a bad person. Vick was given a gift. He has an opportunity to play a sport that he loves AND get paid for it. Who wouldn't like to get paid a livable wage to do something they love?