I'm going to be held back for two years.
Why are you going to be held behind for two years?
I'm actually pretty stupid, I mean I can't even balance my own bank account.
I'm sorry you're struggling to much, but you need to keep trying your hardest. You are losing a lot of your life by not trying and constantly failing, and your peers will think you're dumb for constantly repeating grades.
I don't care what people think of me. I think I'm fine being stupid.
It sounds like you don't have much passion to better yourself in life. You should always strive to do and be better.