Nihilism may not be incompatible with happiness but after reading this post I still believe that I experience legitimate existential angst. It occurs at unpredictable moments, but more often exciting ones: during coitus, staring at a beautiful sunrise, listening to the climax of a beautiful piece of music; but also during mundane tasks like brushing my teeth. I experience an overwhelming sense of angst and meaninglessness. The feeling of arbitrariness, embodied as raw emotion, overwhelms all other sensation. Usually I am able to quickly recover, at least operationally.
I don’t think I’m depressed and I’ve gotten better since the visceral discovery of nihilism back in high-school, but I suspect this will never go away.