Why are older people less likely to change their core beliefs?

Recently, I had a conversation with a long-time committed leftist who "blinked" when confronted with the fact that collectivism always fails, and it fails because the underlying theory is wrong in principle. Many people, particularly older people, are unwilling to reconsider their core views, however. As to the reason why, my hypothesis is that older people have significant sunk costs in their philosophy, such that they could not psychologically survive the realization that they were so wrong for so many decades. Is that right? If so, what can be done to help them change for the better, if anything?