[user104658]

Originally Posted by Niamh.

I vaguely remember watching that when It came out, I don't really remember the plot very well though

I don't think it's exactly the same obviously but

Spoiler:

A guy with below-average intelligence is used in an experiment by a random scientist who thinks he can make him smarter by unlocking his brain, but it goes too far and he becomes super intelligent, starts developing strange abilities, and in the end basically abandons his body and "uploads" his mind.

Obviously not the same but suspiciously similar in concept and conclusion! So the ending of Lucy isn't just nonsense, it's unoriginal nonsense.