Computation market prices can and do go down. But since society can grow almost infinitely quickly (by copying ems), from an em's POV it's more relevant to say that everything else's price goes up.

A society of super-optimizers better have a darn good reason for allowing resource use to outstrip N^3. (And no doubt, they often will.)

A society of super-optimizers that regulates itself in a way resulting in mass death either isn't so much super-optimized, or has a rather (to me) unsavory set of values.

Otherwise we might as well talk about a society of <10 planet-sized Jupiter brains, each owning its physical computing substrate and so immortal short of violent death.

Past a certain point of optimization power, all deaths become either violent or voluntary.