why isnt mdma as addictive as meth/coke/heroin?

someone does something and they want to do it again, is usually cuz they had such a good time the first time and there chasing that again. herion/perks or w.e ppl get addicted cuz they need to have that feeling again or there not happy, most ppl i know dont have fun on it they nod out or feel good.. molly or x u can get addicted but its mostly cuz u wanna have fun again not cuz ur body is telling u need it like others. id rather do molly then extacy and both rather then downers like perks or xanax.