Do you really think ET's have migrated there for the light show?
For the energy - there is so much virtually unlimited in any quantities that anything could be built - time moves slower as you approach the accretion disk. For a mechanoid that is time enough to develop things we cannot fathom or even imagine - like rebuilding themselves into protons and anti-protons to out live the universe ... and so on. If you want to survive the heat death of the universe its either that or travel to The Great Attractor - the spot were all matter is heading towards at increasing speed - and hope someone opened a door to another universe.