Oh there's other potentially more profitable ways than just making X illegal.
For example, you can restrict, license and tax the everloving shit out of it. You could treat X in the same manner you treat say, meth precurors and prosecute and feed the prison system accordingly there.
Anything you can legally purchase today, can be illegal to purchase tomorrow, By law. Take the UK talking today about banning "All legal highs". Seriously. This is the level we're working with over here with drug legislation. What the hell is this supposed to cover exactly? Well, nearly anything and everything to a canny copper. In the meanwhile you've created swathes of criminals to be caught and punished as law dictates.
NO MORE TEA!