Two decent books I've read on this topic, especially the former: "Rare Earth" and "The Erie Silence."
Life is probably very common, technological civilizations extremely rare. ET will most likely be AI due to the vastly faster "evolution" of that technology, something that Elon Musk, Stephen Hawking, and others are now concerned about with respect to human dominance/survival.
The Last Question by Isaac Asimov
https://www.multivax.com/last_question.html
The window of opportunity for the detection of technological civilizations via their electromagnetic emissions is
extremely short. Only 80 years after we became detectable, we are rapidly becoming undetectable at great distances due to more advanced and efficient communications technologies. Plus, not knowing the cultures of possibly
far more advanced cultures, only stupid civilizations intentionally broadcast their presence by powerful directional broadcasts although the short duration and highly directional nature of those would make the likelihood of their detection absolutely minuscule. One very difficult, future detection method is via spectrometry of atmospheric pollutants possibly generated by technological civilizations. However, once again, advanced civilizations may not generate any. They would have, for instance, at least developed fusion as their energy source. If they've built a Dyson Sphere around their star:
https://en.wikipedia.org/wiki/Dyson_sphere
They might be detected by that.
Considering all that and more, the fact that we haven't detected anyone else yet doesn't surprise me in the slightest even though I'm virtually certain due to the odds that there are plenty of them out there. Actually, I'd be far more surprised if we did detect them.