Good primer on the Fermi Paradox. Just what I needed. If you look at the human race (the only example we have) it appears that a species that has advanced to the point of space travel is also at the point of damaging its ecosystem to the point of threatening its own extinction. This was the premise of a great little story called The Fermi Paradox Is Our Business Model by Charlie Jane Anders.
Even if a species manages to safely navigate this point in its development, coming up with a stable society that includes space travel, the distances in space are exceedingly vast. Perhaps when we look at space, we're seeing many planets teeming with life that we can never get to, while they can never get to us. It might be just as well. We don't get along well ourselves; how well can we be expected to get along with aliens?
Not that we see those planets as they are now. We see them as they were, millions of years ago.