The issue I have with Dyson Sphere's is in 1960 the idea of the singularity hadn't really been floated. I think it is far more likely that civilizations either die or upload.
It is not clear to me how that is a contradiction. An uploaded civilization may still desire more computational power, and unless there's an infinite computation escape hatch in physics (and there is currently not even a trace of such a thing), that's going to involve getting more energy from the star. On an exponential growth curve, even improving your civilization's energy efficiency by a factor of a hundred quadrillion still only buys you a blip on the scale on cosmic time scales before you start wanting to expand again.