I highly recommend Stephen Webb's book Where Is Everybody? on the pros and cons of these arguments about the Fermi paradox. For example, your point is reasonabl

I highly recommend Stephen Webb's book Where Is Everybody? on the pros and cons of these arguments about the Fermi paradox. For example, your point is reasonable regarding the overall scale of the universe and life in other galaxies. Yet if life naturally arose on our planet in a relatively short habitable window (<100MM), considering the number of other potential habitable planets in our own galaxy alone, many scientists find it unreasonable to think that we would be the first or only life (and/or intelligent life, depending on assumptions) in our galaxy, within however many billions of years we are into a habitable universal time window. There are fairly conservative calculations that argue we should at least have seen evidence or been visited by at least one civilization trying to escape threats to its own planet within our own galaxy.