I want to believe the MC is gonna speed up his endification soon like the cover and either he's gonna really go for it in reaching the peak, but having to do it faster than expected because he's getting worse faster than he should, or he's gonna eventually unlock something to do with willpower that lets him revert back somewhat but in exange, the next time he endifies himself a bit more of him gets worse, the goal becoming to use it as sparingly as he can.
Or this is just going to continue getting even more frustrating, making people lose interest and axing this before it reaches a good milestone. Could go either way but I don't think so far the author is trying to "shounenfy" the endification power.