I'm sure that a lot of people would be willing to help others, but to support people to stay at home for upwards of sixteen years is a big ask.
I don't think it's being mean-spirited to think that it's unfair to expect the child-free to support parents to that extent. Pay for education, maternity care and pay, nurseries, yes - but more than sixteen years of staying at home whilst children are at school is asking a lot, and not wanting to do so is not at all synonymous with not wanting children to have a decent start in life.
Children also learn by example, and if they see their mothers working to support them, and getting satisfaction from a career or job (or just from being independent), it could be argued that that is giving them a good start, too.
Another Tired Kicking For The Sick And Disabled By Rishi