I think there's a part of the HN population that has delusions of becoming billionaires one day, so they talk about tens of millions like it's not much. They'll likely never have either.
Granted, this threshold is less than $10M, but it isn't orders of magnitude less
All of which is to say that it is basically impossible to stay in the Bay long-term unless you make an absolute fuckton of money.
Well, you do have two other options.
One is to commute in 2hr or more every day. Which a lot of service workers have to do.
The other is to share a house or apartment with roommates (if you're single) or with another family (surprisingly common, because what else can you do?).
These are both lifestyle decisions that differ substantially from what most people think of as "normal", past your 20s.
What I'm saying is, merely living a "normal middle class" lifestyle in the Bay requires absurd money. So I can understand why people act like absurd money is normal.
Rent is like $3k/mo, so $36k/yr. Say you have modest living expenses of another $34k/yr. Now you're at $70k/yr to break even. That leaves you with $90k to save/compound.
So, ok, you're doing very well as a renter with $5M invested, even in the Bay Area. And, given that you have more than twice the income you need, you'd probably be ok with only $2-2.5M. As in, breaking even with passive income.
Which would work so long as you don't want to own a house, and so long as markets don't melt down. That extra security seems to cost extra.
If you used cromd's figures of $5M in funds and lifestyle expenses of $400k/year you'd have spent ~80% of the principal (although you'd probably have reigned in your spending unless you were mad)
A boat doesn't just need to survive the harbour's average water level - it needs to survive low tide and high tide.
For me, financial security means something more like: money will be low on my list of problems. I could get more money by turning my attention there. I might have to work, but it could be some low-stress job, and losing it isn't a big deal. I could afford extra care for an elderly parent. I won't be knocked out by most random things that pop up, specific to my personal life, though I can't control what happens to my country etc.
For some, it means they don't have to work at all, and can't be ruined by market downturns that last decades. And further for some others, it means they can survive wars and societal collapse.
I think both are valid to wish for, though at a certain point it's a burden on yourself to control things you can't control. If there's a 1.1% chance of widespread nuclear war in our lifetime, and you want to be 99% certain your lifestyle won't take a hit, one needs to save and spend a ton to be able to weather it all.