I understand, but for all he knows, there could be planets out there teaming with two headed baboons or human like creatures that have no desire to build a space craft and travel to the stars, or a race of creatures with little intelligence, (like those in DC) or maybe these creatures life span is only 10 years, and they don't have the mental ability for space travel, or it's taboo or they just don't have the natural resources to build a craft etc... Hehehe.
I for one, believe that there is probably a whole lot of life, right within our very own Milky Way galaxy. We just don't know what is going on the other side of the galaxy, say 80,000 light years aways, on the surface of some small planet. Not yet anyway.