Perhaps, in retrospect, there would be little motivation even for malevolent extraterrestrials to attack the Earth; perhaps, after a preliminary survey, they might decide it is more expedient just to be patient for a little while and wait for us to self-destruct.
Maybe it's a little early. Maybe the time is not quite yet. But those other worlds - promising untold opportunities - beckon. Silently, they orbit the Sun, waiting.