And that's just for 1 person. Your spouse (if you have one) is most likely also working in a white collar job as well which we'll impute with the median income in they Bay which is $75k [1], but in reality is an underestimate as your spouse is likely to work in a tech, biotech, medicine, finance, accounting, healthcare, or government adjacent field which would increase their income significantly.
Using the $75k imputed spousal take-home, that would make your joint household income after tax and both maxing out Roth 401k to be around $180,000.
Renting a 2-4 bedroom single family home in a family friendly locale like the Tri-Valley, South Bay, or the Peninsula comes out to around $4.5K/mo, which means you have around $126K per year.
Let's remove $26K due to household expenses (which I personally think is excessive - my household operates on $1.5K/mo and we live pretty extravagantly in San Francisco) and you end up with $100K in cash after a fully loaded 401K, taxes, and rent.
Put around 60-65% of that in a couple ETFs (expecting around 5%-9% returns) and the remaining 35-40% in liquid cash savings.
That means you have around $60K per year invested in easy to liquidate assets, around $50K per year invested for retirement, and around $40K per year in hard cash.
This is why it works and why most people in Tech still remain in the Bay or NYC (similar math).
If you cannot live lean with a 3 person household using the math above in the Bay Area - a region where the MEDIAN household income is $137K [2] - then frankly you have major character defects.
[0] - https://www.levels.fyi/t/software-engineer/locations/san-fra...
[1] - https://www.bayareaequityatlas.org/indicators/median-earning...