Robert Freitas wrote articles about 20 years ago that explained many problems with the lack of logic in the Fermi paradox
I think that our current observations are incredibly incomplete. We are still just finding planets larger than Pluto in our own solar system. We often do not detect objects that are larger than a kilometer in size that in astronomical terms just miss our planet within one million kilometers
So an alien deathstar size object (120 kilometers in diameter) could be passing by Saturn and we would probably not know it. If it happened over 10 years ago we would have definitely missed it. 50 years ago it could have passed by Mars and we would have been clueless.
Why have aliens not visited us and announced their presence? I think it is because we are relatively boring to them and if they had done it anytime from 1400 and earlier we would have not understood it or collectively forgotten. I think it is foolish to argue that maybe they destroyed themselves. It is like we have an anthill and say hey we don't remember anyone visiting us this week, it must mean we are the only life on the planet. We sent out ants to two neighbouring hills (the moon and mars) and stood at the top of our hill and looked around.
We need better technology. We could not detect our own radio waves if we set up similar receivers in the nearest solar system. The signals fade into the background.
Right now we have the first term of the Drake equation with any certainty R* is the rate of star formation in our galaxy
We need to nail down the other drake equation parameters for our galaxy by surveying it. Then we can extrapolate to the universe.
fp is the fraction of those stars which have planets
ne is average number of planets which can potentially support life per star that has planets
World imagers, Hyper telescopes and Magnetically inflated cable structures could be built over the next 20-30 years. Even without molecular nanotechnology we could have telescopes in space that are 1km-10km in size and then arrayed together. We would be able look in detail out hundreds of light years. By in detail, I mean directly imaging continents on earth like planets.
Molecular nanotechnology enhance the above systems and we could have really big telescope arrays 5 years after the first assembler. We would be able to look in detail out thousands of light years and maybe tens of thousands of light years.
fl is the fraction of the above which actually go on to develop life
Remote spectral scans of an atmosphere could give a pretty good idea about the above term.
fi is the fraction of the above which actually go on to develop intelligent life
We have to go out into the galaxy and find them.
fc is the fraction of the above which are willing and able to communicate
We have to go out and try to talk to them
L is the expected lifetime of such a civilization
We can find evidence of a dead civilization and perform some archeology to determine when they died.