There are still incomprehensible numbers of stars, and awe-inspiring distances between them. Even if acceleration is cheap, there are only a few thousand stars

There are still incomprehensible numbers of stars, and awe-inspiring distances between them. Even if acceleration is cheap, there are only a few thousand stars that would have been reached by any human-produced signal yet -- and the chances of one of those containing intelligent life, the chances of those containing intelligent life that happens to detect our signal, the chances of those containing intelligent life that detects our signal and also has a space program, the chances of those containing intelligent life that detects our signal, has a space program, and decides to mount a voyage to Earth, the chances of those containing intelligent life that detects our signal, has a space program, decides to mount a voyage to Earth, and would have been able to get anywhere close by now...