The reason we haven't found aliens is because any advanced civilization destroys itself.

That the stereotypical Alien “encounter”, involving abduction, probing, and other experiments, are not aliens, but rather humans, from the future, coming back to try and figure out why we stopped being able to reproduce. Furthermore, that concludes that whatever brings about the potential fall of man has already begun.

I love/hate the idea that the existence of the uncanny valley implies the existence of something that looks human but wasn't quite human and we needed to fear it.

There's plastic in our blood and every piece of tech listens to us.

And nobody really cares.

Human are nothing more than a virus destroying the larger organism earth. Earth will eventually get a fever in an attempt to rid herself of us.

Colonization of Africa. Probably not the worst necessarily, but one with massive and far reaching implications.

An entire continent set back for generations socially, culturally, and economically.