Whenever a discussion (drunk or sober; it doesn’t matter which) about aliens existing comes up, it always comes down to the point about why they never visit. You’ve got one camp of people that say that there are no such things as aliens, because we’ve never seen them. The other side will tell you that aliens are real and their uncle saw one, but there’s a cover up or some shit.
Personally, I like to believe that we’re not alone out there, but based on the evidence, or lack of, it’s hard to be sure.
But, there are a lot of reasons why, if there really are little green men out there, they don’t stop to say hi, and it all starts with the “Fermi Paradox.”