It is extremely unlikely that even if there has ever been an intelligent life there, it's at a similar civilization development stage to ours, today. It took ~4B years to get where we are today on this planet, but the age of our civilization is only about a hundred thousand years. In a few thousand years our civilization will advance so much that it will be completely unrecognizable (or cease to exist), so you're asking for either an overlap in two extremely short historical windows, on planets developing independently for billions of years, or you expect their civilization to be stuck at about our level for many millions of years.
This is why things like SETI (and arecibo for finding ETs) make no sense. I compare it to using a telescope in 1850 to look for https://en.wikipedia.org/wiki/Flag_semaphore in space. The technology we have to send signals today will look completely pathetic to us when we look back on them in 50 years. Why would we expect ETs to use technology that we ourselves will abandon completely in the relative blink of an eye?
Well, for one, the doomed endeavors (if it actually is) are often worthwhile for the following reasons:
-The technology that stems from attempting to answer the problem.
-The unforeseen consequences - i.e. Maybe someday we'll reach technology that can detect signals in a more advanced way than we can currently and, through recording data from the past, have captured a signal years before that technology exists.
-How many people buy into lotteries despite having awful odds? The odds may be bad, but it's non-zero.
There is no reason to think we will be using grossly non-directional broadcast EM waves in 50 years for communication, and certainly not in 100 years. It's far more likely we will have extremely high bandwidth over very low distances, since that allows for far more bandwidth in aggregate (since you aren't interfering with other users on the same spectrum).
Or we might have moved on to laser (highly directional) or something nobody has thought of yet. I promise you we won't be using some kind of nondirectional, multi trillion watt carrier-based radio contraption that we would have to be using to be spotted by something like SETI on alien world.
