ME, AFTER A LONG DRAG ON SOME HERB MY GRASS TYPE POKEMON MADE: It's just like, how can Giovanni be the mafioso to worry about in a world where all the veterinarians and all the cops are members of the same family? That's just straight nepotism, you know?
Celadon Game Corner was a front for the Team Rocket Hideout, and made money off of child-gambling
With all the TMs, items, and rare pokemon a 12 year old could wring out of the Game Corner, I don't think they were profiting off the gambling.