A Deepness of Thought
The Fermi paradox is that, if Earth is not unique, there should be many alien civilizations. Given that the galaxy is 13.2 billion years old, has 100 billion stars and is 100,000 light years across, and we should have been contacted. So where are they? One obvious answer is that the Earth is unique and there are no aliens. There are lots of possible explanations for this such as the unexplained evolution of eukaryotic cells.
The other explanation I find plausible is the aliens do not want to contact us.
There are many possible reasons why an alien civilization might not want to contact us. Perhaps they consider it risky. Not so much that we would attack them but that we would give away their location to another civilization that would. Perhaps the universe is a dangerous place and we are being foolish to broadcast that we are here. Another possibility is that the aliens consider us more valuable without contact. Like we are some kind of experiment that will yield useful information.
If we discover aliens, it will be the greatest discovery ever. If we discover aliens do not exist, it will be the greatest discovery ever. Work on this discovery can progress on several fronts. We can build better telescopes, we can send a probe to another star, we can figure out how eukaryotic cells (and thus multi-celled organisms) evolved.