aside from his years as a teacher he owned a pool room in NJ. He was probably never without a nice income that had nothing to do with playing pool. Later he had his cue line and inducements and another pool room in Florida that he had when he died. I don't know what he made from the Miller thing, I am sure not really that much, they had like 20 other commercials running at the same time. It really upped his profile though.
The Miz also made some stock market investments when he was still jn college.
He said he got really lucky.