So, driving while intoxicated (doesn't matter with *what*) is okay!?
Legality does not imply the absence of regulation. Alcohol is legal (though some would prefer it not be) and yet it is regulated. Legality means you don't get put in cuffs when a cop sees you blazing.
As for opiates, ect., there's no way in hell those should be legal. If you have *any* idea what those do to people, you should know how terrible they are.
I haven't heard a convincing argument why people should not be allowed to engage in self-destructive behavior, and why it is society's responsibility to spend money on saving them from themselves (or additionally to hand them welfare checks while they engage in such behavior).
Frankly, I don't buy any of the decriminalization arguements. And yes, I know how some argue that we're inconsistant because we allow smoking. Frankly, I would prefer we outlaw that, too.
See above. Smoking anything has some other issues attached to it, namely the littering and air pollution. In the privacy of one's home or on private property whose owner has allowed it, I don't know of a convincing reason why moral crusaders such as yourself should be able to prevent people from engaging in such activities.