My DM and Dsis were and are sahm. Neither has sought to think about their future. Both married twice and the first DHs managed to get away with paying FA maintenance and building up good assets/pensions etc that DM and Dsis cannot access.
Their second DHs were/are poor earners. Neither has a good pension, my Dsis is not doing anything to plan for hers and it is too late for my DM.
In my DMs case, her current husband is sick, with no insurance or anything. They live in a privately rented house that my DM will not be able to afford when her DH passes away.
Both my DM and my Dsis look, from. My view, to have a future of struggle or will have to rely on others.
I couldn't stand the thought of being reliant on anyone. I am not lucky enough to have not ever been let down, so I was always self protective. I never gave up my career, I am paying into my pension pot and trying to get our mortgage clear. My DH unexpectedly is sick now, with a disease that usually affects much older people and every year I have him is a blessing but I can't rely on his earnings, and I am so pleased and relieved that I chose not to be a sahm and maintain my own financial independence. I felt horrible working when my DC were so little, but it is paying off now. When it is needed. I would never have predicted the future I and my DC face.
A life that is lived relying on the protection provided by others, even with the security of marriage, is not ever really safe. Sometimes it works out, but not every time and there are no guarantees.