Plus, to know that they're there, they would have to have discovered radio too, recognised that these radio signals are artificial, and have sent something back. Which we might not have heard because they're too weak or we're listening in the wrong place at the wrong time at the wrong frequency.
As for actually meeting them, that's even more improbable. Look at the trouble we're having trying to get any further than the Moon. Weightlessness is a big problem, you'd need total recycling to provide food and water, the right kind of astronauts that won't go mad from years in a small space, and even if we can solve all that, it's a dangerous universe out there. Outside of the Earth's magnetic field, all those charged particles and other cosmic rays that stars throw out make it like being in a blast of nuclear fallout, which would give all the astronauts cancer. So you need heavy radiation shielding, which means a very heavy spaceship and how would you launch it?
And the distances are so vast that you could never hope to complete any such trip within a human lifetime. Which is why sci-fi authors resort to the idea of hyperspace to get round the limitations of Einstein's theories of relativity. There are some sci-fi authors who haven't done this - Arthur C Clarke never did, and so did Ben Bova in "The Exiles Trilogy". But they're rather in the minority.
Maybe some day it might be discovered that this IS possible in reality, but so far it's not and that's still not about technology, it's about scientific knowledge. Once you have the science, technology is the relatively easy bit afterwards to make use of it, but so far we don't have the science.
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Tom S say: Because the universe is really, really, really, really, really, really, really, really, big.
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User say: how can we find it, if we can't visit our closely neighbors planets, lets say mars? even visiting our moon are too hard to achieve 😳
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