Despite consuming copious amounts of mushrooms, Mario has never been a dealer, per se. Oh, sure, he's always been one to share the wealth—why do you think Toad is always following him around? Kid's a fiend. Mario never sells, though.
One day he'll learn that the money's in slinging narcotics, not princess-saving or professional sports. Then we'll be playing Dope Wars with 'shrooms, stars and blooper ink instead of crack and meth. After all, Mario only deals in the really hard stuff.