A piece of work
A person who has all the help in the world, but still messes everything up. You're a fool if you believe in them. You're a genius if you don't.
My uncle is a piece of work. He had a whole team of engineers, but he still managed to crash his car into a tree.
My mom is a piece of work. She had a personal trainer, but she still couldn't remember how to tie her shoes.
My teacher is a piece of work. She had a whole class of smart kids, but she still couldn't add 2 + 2.