^^ Nobody knows the trouble I've seen.
So, erhm, this civilization builds a Dyson-sphere around their sun and spend the next couple of million years filing it in with their kind.
Meanwhile a whole new civilization spawns from bacteria on the outside...
Which civilization will be victorious in The War of the Dyson Sphere?
I was thinking more of a non-civilization of loners and non-conformists, but there certainly could be an eventual conflict-- especially if any of them fall through the roof.