Just out of curiosity, have you done the traditional narcotics like Crack, meth, heroin?
MDMA certainly produces a profound euphoria, especially the first time, but its not nearly as a reinforcing or reobtainable as the others I mentioned. In my experience, everyone is different.
Crack, meth, and heroin still make my mouth water just thinking of them. MDMA makes me nauseous thinking of it. But I went through a period of extremely reckless MDMA use. I've never been able to get properly high on it ever since.