Tony Hawk isn't a grifter. He is a huge sellout, but not a grifter.
If we're talking about using your skate celebrity to convince your fans to give you money or invest in something you benefit from but know they won't, I'd have to put Lil Stevie's NFTs and meta-real estate at the top. Who else did NFTs? Bob Burquist? I think Tony Hawk did as well, so perhaps he is a grifter.
If we are talking about pros who should have stopped having a pro board, that is hard to quantify. A pro skater's job is to sell skateboards, so even if they stop skating and getting footage (Dill, Rickk, Mike, Sheffey, Arto, and many many more) - if their board sells, then they are kind of doing their job.