benroyce, 
The Fermi Paradox says we should have contacted alien life by now
The Great Filter says we haven't because a civilization's capacity for self-destruction increases to certainty over time
I thought for us it would be an exotic technology or scientific discovery that instantly destroys on a large scale
Nope. Far more depressing and mundane
We simply watched ourselves destroy our climate and lacked the will to do anything about it because someone was making money off it
