Which is it?
Rubbish. Last time cannabis - a known and accepted ingredient in many legal products - was rechristened as "marihuana" by out-of-work ex-Prohibitionists and criminalized with scare stories about crazy Mexicans and white-woman-seducing Negro jazz musicians. (And robbery to pay for drugs is fueled by anti-drug laws keeping prices high.)
Which is it?
Both are true - since drug robbery is much lower when drugs are legal, it's not a motivating factor in making drugs illegal.