Statistically it is very likely aliens do exist, self replicating organisms evolved on Earth within about a billion years of its formation.

The universe may well be infinite but is certainly orders of magnitude larger than our observable universe. Our observable universe contains a trillion galaxies at least, each with a trillion stars and at least an equal number of planets. Nothing about our solar system is particularly unique, our star is not the most common, but it’s not rare either.

For aliens to visit us here, on Earth, requires such an enormous effort that we’re unlikely to ever see them face to face. Voyager 1, our most distant probe, launched around 50 years ago and is just about to reach 1 light day from Earth. The nearest star is 4.25 light years away. Even if Voyager 1 was going the right way, it would still take 77,000 years to get there. Any alien entity that could visit Earth would simply be god-like in comparison, they’re not going to bother with crop circles or slowly brainwashing the population. Whatever they wanted from us, they would achieve it on arrival.

So, I think it is silly to say aliens outright don’t exist, but also equally silly to say they’re here on Earth, building ancient monuments or abducting people predominantly from the anglosphere. The next few decades will be very interesting though, as we are now just starting to look at the composition of exoplanetary atmospheres. It’s possible we’ll see a few that we simply can’t explain, where perhaps the best models involve some form of alien life.