The villain is like the MC of Re:Zero that constantly dies (for very weird reasons) and reborn. To make him worst and unsympathetic, the story just throw how he is a prisoner and that he dies from random stuff when he harm someone. I say "the story just throw" as there were no build up or further explanation as to why he was a prisoner and why he was harming others beside the hint that he is crazy. Now this is possible, but the mere fact we can assume otherwise doesn't sit well for me.

In one of the reborn life, he survive from his lover saving him. His lover died from her hidden disease, he tried to save her by researching on the cure but failed and now on the mission to revive her instead. In the end, he found out a technique of reviving a dead person by sacrificing a suicidal and MC as the most compatible life to exchange.

First off, see how for plot convinience it needs to be MC in this world of 8 billion people.

Sound tragic right? Well to make it less tragic the story flip it last minute and change to how in fact the villain actually just love himself so much and find her as the antidote to him not dying... If you go back, you can see the real reason he kept dying is because he's doing bad deeds. This is a HIGH IQ VILLAIN. Let's assume he never notice the correlation, but he never tested if being lovers with someone else could help? Got to also point out that in raising kids, punising a kid WITHOUT telling them what's wrong is just not the best way to teach someone, we learned this in this time you telling me the future forgot this or is the future agreeing punishment without being clear of the reason is okay.

It just so many holes. And the ironic part for me is that we get to see MC buying the cure for the disease in the system AND rewriting the timeline to one where MC won and is alive.

Oh the reason why villain can't but the medicine? Because the system can't provide discount like the system offered to MC because reasons. And system sacrificing their life for MC.

Entirely going around villain point as to why there are people who have good fate and some who have it bad. And the entire answer of MC of experiencing what it feels like to die and live again and again doesn't really work when the villain is doing that?

And also:

Villain: continuesly die for random reason and so biggest fear is dying

MC: and you said you love your lover

??? I was laughing so hard when the author correlate fear of death to mean he is narcistic and never love his lover. Like what, author needs to touch grass.