The social conservatism about cannabis was created and stoked by propaganda and laws created in large part due to industrial lobbying, if you look back a generation or two.
I looked for studies supporting your statement. The evidence is conflicting, and there appears to be no conclusive evidence one way or the other, although some people certainly are fond of repeating this as if it's fact.
I honestly think the obstacle to Cannabis legalization in the US is social conservatism, not industrial lobbying.