Wasn't it Tony Sivori who wrote:

I see the Fermi Paradox as based on an invalid assumption.

I used to live near the ocean, and would sometimes wade and swim in the sea.
I never saw a shark. Yet I did not exclaim "There are said to be sharks in
here, I don't see them and therefore they probably do not exist." I knew
they were there, but merely beyond the range of my human sensoria.

I believe that is a fairly good analogy to extraterrestrial intelligence.
The size of the universe is such that it is inconceivable that we are the
only technological beings in existence. Yet that same immense size that
assures we are not the only ones also insures that it is improbable that we
will interact with, or even detect them.

One significant difference is that sharks don't have technology, so
their numbers are kept in balance by factors such as the availability of
suitable prey and their innate ability to catch it.

The numbers of a star-travelling technological species may only be
limited by the amount of real estate they occupy. It's possible that
some civilisations may have managed to artificially limit their
populations, but it only takes one star-travelling species to have
failed to inhibit their biological imperative to reproduce, and they'll
occupy every inch of real estate in the galaxy in less than a hundred
million years.

-- 
Mike Williams
Gentleman of Leisure