In my opinion mdma is like any other drug, its the absolute best feeling the first few times and gets progressively less fun as time goes on. Through many reports from many people it is definitely possible to abuse mdma to the point of never being able to enjoy it again. I abused mdma for about two years, once or twice a month sometimes three times a month. The last time I rolled was after a 4 month break and it was just as "magical" as the first time minus the novelty factor. There are many people who used much more heavily then me for longer and have been fine, there are also many people who used less then I did and "lost the magic" and had many negative consequences much more quickly. I think the time frame varies greatly person to person but the end result will be the same, you will not be able to enjoy it if you do not space your doses and avoid taking too much and redosing.