[hot_pastrami]

I've always considered the tendency for people to become "set in their ways" to be mostly psychological, as you are assuming in your scenario... people find a psychological comfort zone, and they resist and resent anything that threatens to disturb that. People put themselves in a rut, and then fall in love with it. It can't be wholly biological, because people are capable of changing at any point in their lives, if they must.

But what of the biological limitations of memory? There is little understanding of how memory functions, but there is much evidence that even when we "forget" things, it's still stored up there somewhere, stuffed in a dusty old trunk which can still be opened and acccessed under the right circumstances. That being the case, it is very likely that there is a maximum capacity for human long-term memory. Once a person hit this barrier, they would be like an Alzheimer's patient, with only the temporary short-term memory to go on. Not much of an existence if you ask me.