Story Issue: Is 20% of the population high enough to kill?

[Belril Duskwalk]

Just to put numbers in perspective here:
50% of the population would be equivalent to the combined populations of China, India, the USA, Indonesia, Brazil and Pakistan (the 6 most populous countries on Earth). That's who gets superpowers.
30% is a little less than the combined populations of China and India. That's how many people die.
20% is a little more than the entire population of China. That's people alive, but without Superpowers after the ritual.

In the immediate aftermath, there is a likelihood of a huge number of car crashes and other accidents (we just killed 30% of the world's population. I guarantee some of them were operating vehicles or in some other way were holding the lives of other people in their hands.) For everyone who didn't get Invincibility or Nigh Invincibility as a power, that's going to be a large number of additional casualties.

Seeing as we can't target who is getting powers and who is dying we've also created a massive number of super-villains, because we did just give superpowers to who knows how many murders, muggers etc. Not even counting people who previously obeyed the law out of fear of consequences which are no longer a concern with the right power pack. And as others have noted, if we kill 30% of the world, we turn the remaining 70% into mourners, most of whom now have an undefined (and possibly uncontrolled) assortment of superpowers. Unless the ritual was nice enough to vaporize the bodies, we now literally have more dead bodies than we know what to do with. Societal upheaval is not only possible, but extremely likely, even without the aliens showing up in a month to try and kill everyone. Casualties won't stop at 30%, they will start at 30% and rise rapidly until (if?) society finds a new balance point. We could potentially be talking about killing half the world to save the other half.

This is quite possibly the craziest of crazy last ditch plans I have ever read. The only way I could get behind it is:
A) if there is literally no other chance to win
AND
B) if we are actually guaranteed a win WITH this plan.

If I were a player in such a game, I think I would spend my time trying to stop the villain while also looking for any plan that is less crazy than his plan.