Most movie ideas are stupid. CB raves about a movie about a guy who dresses up like a bat to run around punching people at night. And about a movie in which a Norse god, a super archer, a rich guy in a metal suit, a super soldier from WW2, and a guy who turns into the jolly green giant when angry fight a team of intergalactic cyborg lizards on flying jet skis. And about a movie in which a team of people risks everything to go into some guy's dreams to convince him to break up his company. Etc. The premise of Lucy presents a low believability threshold compared to plenty of other movies.