The window of opportunity of most species capable of advanced civilization, intelligent or not, is probably much shorter than the time frame required to reach interstellar travel. Life is extremely precarious and it is probably wiped out at enough of a high frequency to ensure life forms do not go anywhere. If we take our planet as an example. We have only one branch of Hominidae in homo that hasn't been wiped out by black swan events--modern humans. It has dodged a lot of bullets to make it only a few 100 thousand years. What time we have left is unknown to us, but it is probably not that long in geological time. All complex life forms probably only exist in a narrow window of time. The Universe not only tries to produce them, it also tries and wipe them out. To exist and to persist is to buck a strong trend. Climate must be stable for an extended period of time. Celestial events cannot come and upset the equilibriums too much.