Oh, aliens probably exist, but the likelihood they are intelligent enough for space travel is close to 0%. Just look at how long life on earth has evolved and how many species there already were, then realize only one species got intelligent enough to understand what space even is.
Life may even be abundant, but it doesn't need to be smart. We may be an anomaly within an anomaly.

Though we are screwed if we find evidence of even a single microbe as its evidence that we haven't survived the hypothetical Great Filter. 

 I don't agree with that. In just 100 years, we went from using horses to sending a person to the moon. 

Given a thousand more years, we could become an intergalactic species, if not sooner. It's a very short period of time in terms of universe.

Agree, there are most probably aliens out there, I doubt they would crash on Earth if they possess the technology to travel between galaxies. 

 I'm unsure what the disagreement is. Nothing seems to conflict with what I posted.