Without a goal, rationality is useless.

Hello. I am software developer. So I already developed a chess MINIMAX and a go MCTS. So I know that a goal is needed to choose the branch to follow. Otherwise you have a binary tree but you don't know which path to follow. The same happens with humans.

Some humans choose religion as their goal. Others choose suicide. Others choose hedonism. Nihilists choose suicide or hedonism. The only other option I see is to take care of your family. There is not other option.

So nihilists in existential crisis are less rational than a bot, because a bot has a goal, but a nihilist has not.