Our luck, we find some ambitious structure around some far sun. Phone them up. By the time we connect, the civ that built it is long gone and replaced by some opportunistic scavenger species who also spotted it. They've found ftl drives laying around or near-light drives and have lots of relativistic time on their pseudohands. These xenoconquistadors show up at our place with the How to Serve Man cookbook.
FF a couple millennia and we may be the opportunists.