Which is why the argument I've heard made recently on air (not by you) that legalizing pot will reduce demand for other drugs falls flat. They DO do different things to you. Take you up, down, sideways. If you want to get a drunk buzz, 20 cups of high caffinated tea or coffee isn't going to get you there.
And there are those who insist that the drug smugglers will just "quit" if they can't smuggle pot. It's not like they'd increase importation of things like xanex, cocaine, or ecstasy.
Speaking from experience, lots of Red Bull will give you a hangover like alcohol though. Stupid procrastination.