There is an "a posteriori" purpose to our existence. We evolved as elaborate mech-suits to protect our DNA and aid in its replication.
I would hypothesize, based on the studies I've read, that high charisma and good looks help more than intelligence for that. Even with your example, Nietzsche himself died without any children.
As for viewing life as mind-numbingly boring, I have an IQ over 160. Beyond the fact that "intelligence" is arguably more of a cultural construct and a subjective value, I think IQ does a decent enough job at measuring what we generally consider important aspects of intelligence. I think it would be fair to say that I'm a highly intelligent person, although "highly" is again subjective, but I am in the top 0.01% of intelligence scores.
I do not find life mind-numbingly boring. This might be because I'm also autistic and have very low charisma, which is apparently common among people with higher IQs, and that carries with it some unique struggles that most people never need to deal with.
I also enjoy studying formal logic, computer science, and information technology, which can all be done for reasonably cheap. I find these topics very engaging and I enjoy talking about them even to those who aren't as knowledgeable or interested in them as I am.
I don't think we should admire people for their intelligence and I don't think the highly intelligent are somehow set apart from the rest of humanity by their intelligence. Yes, having a higher intelligence means that I excel more in technical and mathematical subjects. That's not all there is to life. Trying to divide people into these arbitrary categories only creates division, which leads to unnecessary harm.
Can't we all just be human? Can't we just respect one another as fellow citizens of the world in mutual support of one another's autonomy?