the cold hard fact is he is making millions more than you and is probably the most well known magician today...he is obviously doing something right
TV, and being different.
He's on TV, and no matter how bad something is, if it's on TV it will receive at least some recognition. Laymen are so used to the stereotypical magician pulling rabbits out of hats etc. that a heavy-metal-goth magician is revolutionary to them (and it sort of is) They see him as being different and cool because of his image. That's my theory as to why Criss Angel is popular.