Probably because he was tired of being in the dark. He had an idea and worked hard on it and invented electricity. Thank you Benjamin Franklin. However, I wish they would now invent away to make all electricity cheap and affordable now.
Sorry to be pedantic, but he didn't actually INVENT electricity - it's a natural phenomenon. He merely identified it and came up with ways of harnessing and generating it.
He was so smart inventing electricity was just a way of showing it
He probably was tired of eating cold food and being cold.