It's not a myth that humans do not use their full brain capacity. If we did, we would be like Lucy, we would have powers and transcend our limited physical existence.
So evolution just gave us 90% extra brain matter for no reason?
Doesn't make sense. And no one has ever been able to show the slightest bit of power as depicted in this movie. The Randi challenge (which you could not pass) has never been beaten.