My mother was similar. Grew up in an abusive family, married young to someone who wasn't really good to her, didn't do well in school, never went to college, never had to work, and didn't even do very much as a stay-at-home mom. I grew up in the South, and so "respecting your elders" was something you couldn't really question too much without getting torn apart by everyone else.
Anything that didn't involve watching daytime TV or going shopping was just the most agonizing inconvenience for her, and she never let us forget how ungrateful we were for it. Even when it came to serious medical problems, I'd never get taken to the hospital because it would cut into her spending money. I had to take care of these problems myself much later on in life. She literally said to me, "Your problems were not my responsibility".
Eventually she came into a large sum of money when my father died. My sister and I were still teenagers at the time. She decided to abandon us and go live it up. When I asked her why she was doing this, she said, "You guys have your whole lives ahead of you! I don't! I need this!" When it came to helping out with any college expenses, she'd refuse, saying "Why should I? What does that do for me?"
In her mind, she was entitled to a life of leisure and fun, for having suffered and worked so hard. She spent a great deal of her free time going on vacation and then calling to complain about the most asinine things like I was some sort of therapist or dumping ground.
To her, working was for peasants. If you had to work for a living, she thought you were low-life scum who wasn't smart enough to get rich young. Education was for snobs and arrogant know-nothings who didn't understand how things "really" were. Whenever she had a physical ailment, it was never anything typical -- she would always claim that it was some really rare form of this-or-that and the doctors were too dumb to figure it out. She'd make up stories about how everyone was always hitting on her. She suffered more than anyone, deserved more than anyone, and genuinely believed she was a good person who was constantly under attack by the world.
She's one of the most self-entitled people I know -- basically a huge parasite, both financially and emotionally. I've wondered what our relationship would be like now that I'm a grown adult with my own stable finances, since I would no longer "need" anything from her in a motherly capacity. I don't think much would change because she'd still feel entitled and ask me for money. When I first went NC with her, she threatened to sue me for an absurd sum to compensate her for "everything she spent raising me." It made no sense because not only did she not ever work for a living, but the number was grossly over-inflated, let alone hilariously unenforceable. Basically she feels like everyone in the world owes her for something.
On some level, I feel sorry for her. Despite her constant vacationing, I think she is dead inside and doesn't know how to feel happiness or empathy. It's like she's in constant survival mode, and I attribute that to her upbringing and marriage. I understand why she is the way she is, but it doesn't mean I forgive her or want anything to do with her.