The physicist David Deutsch makes the point that there is no real way to distinguish a consistent, convincing virtual reality from reality itself.

Therefore, there is no real moral difference between richly populating such virtual worlds (once we can construct them--we can't quite, yet) and populating actual other planets. Nick Bostrom would say that even using the word "actual" is probably wrong, since we're likely living in a simulation already.

There's a simpler (maybe too obvious) answer to the Fermi Paradox: the window of time in which it seems worthwhile to communicate with aliens or to settle the galaxy is exceedingly brief.