There is nothing inherently unhappy about nihilism or what Nietzsche wrote about. Personally, going into existentialism/nihilism has felt freeing since I do not feel obligated to follow societies view on what happiness is or how I'm supposed to have fun or that I have to share a common set of morals. TL;DR "The universe certainly doesn't give a shit, so why not have a bit of fun before it's over?"