He didn’t wear the full Ghostface costume though, so perhaps he couldn’t find the rest or never had it, either way, the mask came in handy.
He didn’t take any chances either, in addition to covering his face he even wore gloves to make sure he couldn’t be identified in any way.
This individual opted for a fun movie reference when collecting his winnings. Maybe he’s a fan of Wes Craven’s movie or maybe this was just the mask he had.