Fear is a complex emotion, capable of bringing even the most powerful individuals to their knees. Fear is like war in the way that an organism like humans can't go long without it. What, then, is the purpose of this? Protection yes. Perhaps it was a gift, perhaps a curse. Fear in society is just as present as happiness. And the happier one is, the more they may fear. Perhaps, the more we come to terms with the certainty of death, the less we have to lose, and thus, the less we have to fear. Understanding of our short time on this rock in space holds other benefits. The more depressed somebody is for example, the better they might score on tests of wisdom and realism. An understanding of the truths of the universe is depressing yes. But this is positively correlated with intelligence. The less you fear, the smarter you can push yourself to be. The less you fear, the stronger you become. The less you fear, the more your own mind wishes to destroy itself.