First point: fair enough, I see the flaw. But then we're changing to a more ethical dilemma: does a charismatic person deserve more chance to live?
Second point: with half the population left, there is more time to solve things (caused by humanity). Global warming, for example, will likely be solved by just the snap alone.
Maybe he could have made it that every female can only bare 2 children, that would gradually reduce population. But that would put a huge strain on the younger generation to take care of the elder.
Trying your best and doing it right are 2 different things. It is time this butthurt world re-understands this. Someone should have told her she sucks at it. And yes, it would hurt her feelings but also opening up opportunities for her to pursue something else she will, undoubtedly, be better at.
She can still dance like this if she wants to with all the passion in her heart, but break dance competition, nope.