Not sure how to convince them. Perhaps with changing social security so that your social security benefits are enhanced by the number of children you have paying THEIR taxes.
When the current system collapses, those who have lots of family who care about them are more likely to survive. Elderly childless people will likely to have nobody who is sufficiently interested in them to share what they have, in which case they die.
I can accept the idea of enhancements to benefits.
I’m not arguing with you over the need; just showing what you’re up against.
We won’t make any headway with young women today by simply exhorting them to some equivalent of ‘just lie back and think of England’.
(More’s the pity ;-)