Both my grand parents were retired by 65 (one retired at 63). Both have public retirement plans that allowed them to live well. Both my grandmas still worked at home and did everything while my grandpas enjoyed their hobbies and leisure time. When their health become worse, my grandmas (and my mother and aunts) took care of them. My gradnmas are cared by my mother and aunts but they "retired" way older than my grandpas since they always were expected to do everything at home and once my gradnpas didn't went to work, their workload increased. Surprise!

My grandpas and grandmas experience is the norm in my country (and Europe). It is rare that a good father (or an average one) is destitute. It is not that rare if a bad one is. So if you want your children to care for you, you need to care for your children. And caring is not just giving them money, but spending time with them. Now, relationship with children is not marriage, is relationship with children as persons separated from the mother. And the quality of a marriage affects the willingness of someone to take care of you in your old age. And quality of a marriage is not only about money. How do you treat your wife? Does she feel appreaciated? Many men feel that by working hard and making money, that is enough. But no, there are other things. Some small like saying "thank you" when you are presented a warm meal and other are about little nice gestures.

Honestly, I think that many men who complain about marriage, should learn how to do house chores and not marry instead of complaining. But many have enjoyed being cared for while not appreacieting it. Their wives grow tired of that and divorce the second their children no longer need economic support (which is the only thing that they were getting in the marriage). Then men complain about being left alone and not having their wives taking care of them. But while their wives were doing that, they were being rude to them, insulting them, controlling them, telling them that they were doing nothing and treating them badly. so the wives endured that for their children. Children saw that and took them with them. But why children don't take their father? Many children do take their fathers too. If they don't it is because they probably saw what their father was like and didn't like it.

It is not normal for children to abandon fathers. If that happens, something was wrong before the children grow up. Maybe father was homophobe and children gay, maybe father is mysoginist and daughter doesn't want to keep being abused for being female, maybe father never cared for them and attended their events, not asked about them and they feel disconected... But most people with normal father would tell you that they would care for their fathers. That is the norm. To the point that in your story I wonder, why the children take the mother but not the father? This is a missing-missing reasons.