I have known a number of old ladies who can seem quite selfish and even manipulative, and I have concluded that it's a sort of self-preservation instinct for some. Living alone and/or aware of becoming weaker and more vulnerable, they concentrate on their own needs and on how best to get others to help them - using charm, persuasion, threats, money or emotional blackmail as necessary. They focus on themselves because no one else does.
I hope I don't end up that, but I can see why it happens when so many old people live completely on their own, often far from family members.