Why?
Most of our communication relies on radiowaves... even communication to/from space. Now looking at history, we've known and used radiowaves for maybe a 100 years, and considering the current enviromental trends, we might be using it for eg. 500 more, before we die out. Or maybe 10.000. Mathematically it doesn't really matter a lot.
Now look at the waves we've been sending out... a if we assume "the world ends" in 500 years, in a million years, there will be a 600 light-year "thin" shell of a 1mio light years sphere travelling away from earth, attenuated by the square law (twice the distance, 1/4 of the power).
What are the chances, that the thin shell of radiowaves hits some other culture, on some other world, in their "600 years of power", that are able to detect those waves, and actually come visit us (if we're still alive, which we're probably not).
Our world might be everything to us, but in a universal scale, our world compared to the universe is like an atom to our body... utterly insignificant.