I can't figure out the math in the original article. He owed $2 million when he left in December 2016 and made payments for 2.5 years. He also got a $1.1 million loan from GT specifically to help pay down the buyout. But somehow the balance is $1.5 million being, I assume, 2.5/4 years through payments. Either payments were really low or there was an extremely high interest rate.
The complaint in Oregon state court isn't available. Stansbury could have an honest dispute with OSU over the contract. If he has money trouble, then it could be bad investments, spending, gambling, divorce, etc. Who knows.