Telescopes aren't magic, and space is big. There are 100 billion+ stars in the galaxy. Within a 100 light-year radius, there are 27 ( https://en.wikipedia.org/wiki/List_of_star_systems_within_95... ). Nobody's looking at Earth. If any hypothetical civilization were to find our system, it would be by blanketing the entire galaxy in 100 billion drones and checking every single star, in which case the dark forest doesn't matter anyway.