@PoliteEagle I haven't read the full thread but I'm going to assume you are early 30s and live in London.
I'm late 40s. So of the generation where a career is not for life and old enough to have seen the good and bad banking days.
Almost all of my friends exclusively went to top unis and we all did grad schemes at various city firms. I myself worked in Sales at a European bank in the City, so I knew and know plenty of former and current traders, researchers and sales bankers.
90% of my cohort were married before 35 and living the dream. Big salaries, lovely houses and holidays. Plenty of the wives were SAHM. Of that 90%, the majority (men and women) are no longer in the industry through no choice of their own. It is very difficult to have a long term city career now. Ask yourself, how many 50+ year old bankers do you see around? The challenge is that if you don't manage to climb the ladder and make it to the senior echelons, you tend to be made redundant or managed out. So what happens is that these city careers end up being very short for the majority of people. Most are lucky to get 25 years.
This is primarily one of the reasons why wiser people in the industry now seek partners that are more equal from a career perspective. Everyone knows that city careers don't have the longevity they used to.
My advice to you is definitely to aspire to being a SAHM if that is what you want, but I'd recommend you also be willing and able to bring something to the table as life will almost certainly mean you need a plan B.
One of my friends was similar to you. She quit her banking job to be a SAHM to 2 toddlers whilst her trader husband continued to work. He lost his job 3 years later and couldn't find anything in London. They are now expats in an offshore location whilst they rent out their Surrey house.