Look at all those stars in the sky!
There are countless stars out there circulating around in hundreds of billions of galaxies.
Imagine how many of those stars have planets circling them.
Then imagine how may of those stars have water on them.
And how many of those planets with water have developed life?
Then how many of those planets have life that has evolved to a level of high intelligence?
And how many of those planets inhabited by creatures with high intelligence have developed advanced civilizations?
And then imagine how many of those planets inhabited by creatures with high intelligence that have developed advanced civilizations have technologies that let them expand their impact on their planet to the point that they bring about their own extinction?
This is a potential reason why SETI has turned up zilch so far, the Drake equation notwithstanding.
Earth civilization is probably unlikely to survive past our fission era unless some attitudes change with regards to sustainability and sharing. Interestingly, the Vela satellite program and subsequent Vela Incident where satellite data indicated clandestine nuclear testing serves to highlight the sensitive nature of all these matters in our Nuclear Era. Just imagine, among those stars and galaxies, we detect a few thousand vela-like double gamma ray bursts. Does this indicate the ignition of new stars or the death of Darwinism on a few isolated planets. The big question is whether Corporations or Humans should decide the issue.