Has SETI actually found anything scientifically useful? (This is an honest question.)
Yes, it's found a wealth of evidence that there aren't currently alien radio signals being beamed at us. At least, in the directions we've looked, at the frequencies we've checked, within our feeble human understanding of what a signal should look like, we haven't seen any signals. That's useful information. But the returns rapidly diminish. The first thirty seconds you use checking to see if your car keys are under…
Also, as the exoplanet hunt gets better and better, SETI gets more and more data about which stars are the best ones to look at.