It's just you. There may be various reasons for a civilization to leave its planetary system. Its host star may be dying and turning into red giant. A nearby star may be close to going supernova or hypernova. The civilization may send its own space explorers on a passing by free-floating planet. For example, if the civilization's scientists determine that there is a hypervelocity free-floating planet passing through their Oort cloud and heading to a nearby star, they may send their machines to ride the free-floating planet to that star to study it. Why would not they catch a ride when an opportunity presents itself?