I'm planning to score the exam papers without actually reading them.
That's not fair to the students. Why do you want to do that to them?
I want to be able to leave college as soon as I can to work as a professional gambler.
You shouldn't be lying to your students in that way. You could ruin their grade point average by giving them a bad grade just for fun. You should want to leave the school on a good note in case you ever need to return.
I'll never need to return.
Your students worked hard, and it's not acceptable to just make up their grades. You might think you'll never need a reference from this job, but you can't know that right now.