I like the math idea... Life is, apparently, likely anywhere within the Goldilocks zones for gravity, water and air. Multicellular life is highly unlikely. Intelligence, vanishingly rare, perhaps.

Planets in such zones may be vanishingly rare.

But this is a biiiiiiiiig universe. The chances of it having only happened once? Infinitesimal.

But the likelihood of us ever *encounter* such other intelligences, infinitesimal again.

So I don't worry about it. I just assume the galaxy is full of life but it's spread out and unlikely to encounter us.