I could simply respond with "sorry to hear you upset yourself by considering these people entitled", and it would have about the same merit.
It's like telling somebody after a close relative or some else dear to them died that what, did they expect that person would live forever? No, do you?
Do you genuinely think their feelings of betrayal stem from an unreasonable notion of the world? Have you at all considered that the expectations they harbored were not 100% of their own creation?