For me I really do enjoy watching some of the Locking picking lawyers content and he is an expert when it comes to picking locks!
Another few are mental outlaw (although I think everyone knows of him here) and Steven Bridges who makes videos on card counting at casinos and he shows how much he wins/loses from playing
Niche
2.07M subscribers
OP’s example was lockpickinglawyer at 4.39M, YouTube is just a bigger platform than it used to be