Maybe the reason is boredom. Imagine a posthuman civilization where everyone is part of a hivemind with near-infinite computing power; everyone is connected, there are no secrets or privacy and no one is different or has different knowledge than anyone else.
What would be the point of individual existence in that case?
What would you do in their shoes?
I don't know about you but I'd spin up a nice ultra-realistic MMO or simulation and plug myself in (maybe with some friends, if that concept even makes sense) with enough suspension of disbelief and/or temporary amnesia to actually believe its the real thing.
After a "lifetime" of playing the game, I come out with unique experiences and maybe more knowledge to share or not with the hivemind.