A big mistake many people make is to take the "caring for other people" for granted.
They do not understand that thing like "Caring" must be earned, it is never just "given". So they wrongly assume that people will go on and "care" for them without ever having to do something in return or reward them properly.
Of course, since it is a false premise, when the "caring" never comes because they never do anything to earn it ( and keep the balance straight ) they blame anyone but themselves, without ever revising or reviewing their false premises.