There really is sooooo much to take into consideration that generally isn't.
Point: the distances involved in space travel are vast beyond imagining. The closest star is approximately 24 trillion miles away. At 186,000 MPS that's well over 4 years, and you are not getting to that speed, period. So best possible would be over 10 years for a fly-by? Why bother?
Point: given the enormous amount of time it would take to get from the very closest planet outside our own solar system, there is almost no possibility anything other than an unmanned (for lack of a better term) ship would even be considered.
(sub)Point - the closest star we imagine to be habitable is in the Gliese system, over 110 light years away.
Point: where there is the civilization to create this interstellar, star to star mode of conveyance, there is almost certainly a government that wouldn't want to fund it
I have no doubt at all that there is, or has been, other living beings in our Universe. But we are on an extremely
tiny rock ticked away in the enormous arm of a barred spiral galaxy with some 100 to 400 billion other stars. Why anything would look in our direction is beyond me, if they haven't been searching for literally thousands and thousands of years.