YY - my mum got divorced in the 90s, and I think she was stuck in a kind of first wave thing, in that women older than her who had been reliant on their husbands for financial security were generally OK because they would have stayed married.
She never particularly thought about how being a SAHM gave her financial security - she just assumed that it would be fine because it always was fine for every SAHM she knew. I think actually she just assumed that she would get married again, which she never has (and probably won't now, I assume, though could be wrong of course).
You could call it naivety or even stupidity, but being stupid is not a crime, and she has not set out to intentionally defraud or take advantage of anybody. The only thing she's done wrong is not think towards the future, but nobody ever told her that she would need to do that. It was assumed it would be somebody else's responsibility. She doesn't want to claim benefits, but she can't physically work full time due to old injuries and fatigue, and (bloody social media) has convinced her that doctors are all in conspiracy with government and won't believe her. I cannot persuade her any differently, and previous unsympathetic encounters haven't helped - I think honestly she ought to be getting some kind of PIP or something or at least a medical notice that she can only work certain parameters. However, the main thing is she seems to be stuck in a financial time warp of about 1995 and is amazed when she encounters the real cost of anything today, because she doesn't understand "how anybody is supposed to afford that". She keeps going on about how lovely it will be when she retires and doesn't need to worry about working any more, though I have no idea how she will afford to live then, since she still won't have enough money. I tried to show her the government pension calculator thing and that was no use either.
There is only so much you can do. I try to keep hands off because trying to exert any control, when she clearly does not want me to, is extremely stressful.