I got that quote from Wikipedia’s page on the Fermi Paradox.
Since we only have one example, it’s impossible to know how likely it is for intelligence to evolve on an earthlike planet. But maybe the reason we haven’t yet found intelligent life elsewhere in the cosmos is because smart things quickly kill themselves off.
Think of how close we came to killing every human being on the planet during the Cuban Missile Crisis. That was when only two countries had nukes. As technology improves it’s only going to get easier to manufacture such weapons.
Also we might drown in our own waste.
… Ok no more reading Atomic Rockets, The End of Faith, and Wikipedia after 11:30 for me.