aging
Likely primary cause of aging
Of course aging and death is the strongest motivation that would support some kind of 'upload' of consciousness into a more secure physical structure. It would also solve the population problem.
Hindu lore has in it the notion of an infinite number of life monads, only an infinitesimal number of which can be incarnated at any moment. It is conceivable that an unlimited number of monads might be sequestered in a Mind ample enough. After sequestration, forays into carnal life (for, say, a few hundred years) might be just one of many possible adventures.