I used to be convinced that MDMA was harmless, and had absolutely no connection or concept of bad after effects. I figured complaints of feeling like crap after were people that weren't in fabulous shape like me, who didn't sleep and probably did lots of other drugs. Wrong!
I spent the first 6 months of my MDMA use rolling every weekend (almost), with no ill effects. Eventually, it caught up with me, and I was needing more and more pills each weekend, and the come-up was rough, and I started having every bad after effect in the book.

Point being- don't abuse it. You may get away with it, but it will catch up with you. I regret it now because my 6 month binge resulted in what seems to be permanent "loss of magic"- I still enjoy MDMA quite a bit, but I respond to it differently now. Music does not sound much better, I'm not much more happy, I'm not that social.
I now follow the rules- I did break the rules last summer, and rolled one weekend, followed by the next weekend, and was fine. I'm on a multiple month break now in hopes I will enjoy MDMA more.
I think you can enjoy MDMA for a life time if you respect it, and understand serotonin replenishment is a real thing.