Been there.

Pro baseball player burned me for a couple thousand right after he had signed a contract for 3 mil a year.

Worst part was making an extra trip to their house to do a freebie favor, asking for the final check, and having his trash wife, in front of him, telling me no way they were paying the bill, and "let this be a lesson to you.".

After that, the only way I'd do any work for these overpaid jerks, would be 100% up front.