the validation shouldn’t cause too much lag since game needs to sync up the game states anyways, which is an operation that is inherently way more expensive than any validation anyways (since each frame of the following game states need to adhere to the game rules anyways, there’s already inherently some form of validation). It’s more about not trusting everything the client says the game state should be.
Well it being a criminal money is a plus, a main feature even. I got some from GPU mining ages ago so was selling them at its peak and it’s easily noticable how all the legal way to get money is all so traced and requires you to send your ID, sold them by dealing with buyers directly so no ID required instead.