Not because I doubt their existence, but because it's so incredibly improbable.
Incredibly impossible from the standpoint of our current technology. 100 years ago, the notion of landing a man on the moon or setting probes down on Mars was patently ludicrous, the stuff of Sci-Fi.
I would imagine that we stand out like a sore thumb to races just a few hundred years ahead of us not to mention those that are 1 million years ahead of us.
DEPENDS ON A LOT
OF ASSUMPTIONS
And a lot of . . . blind confidence in one’s assumptions . . . based on . . . next to nothing.
Any alien stupid enough to waste time visiting Earth deserves to be ignored. The smarter ones know the Earth will be destroyed by global warming (or, if not, the best parts are already conquered by mexicans or muslims), and they would be wasting time to visit here.
Here is my thinking.. Why in heck would they travel billions of miles just to pick up some drunk and not land in Washington DC???