The only "gateway effect" with weed is when you realize the government has been lying to you for decades, which leads you to ignore the warnings on other drugs. For example, putting heroin and weed in the same category (Schedule I), making them worse than cocaine and speed (Schedule II). We need to be truthful about which drugs are genuinely dangerous, since some clearly are. The Nixon administration is on record as saying they placed weed on Schedule I as a means of attacking political dissidents and minorities.