1. Parties evolve throughout the evening so that only the "fittest" and "best partiers" are able to keep partying. Weaker partiers end up going home, vomiting, or getting lost.
2. Partying evolution strengthens the party and makes it more fun.
3. Those who attempt to help weaker partiers continue throughout the evening ultimately just slow down the partying evolution and make it less fun for everyone.
Friend 2 (Party Socialist): "C'mon man. It's so much more fun when we all stay together and move at the same pace and split our drinks."
Friend 1 (Party Darwinist): "I believe in Party Darwinism. Leave the weak behind. Only the strong deserve to keep partying."