For property tax, i found this california property tax calculator [0], which says it's $6,490/year ($541/month) for a home assessed at $1M in SF. That brings us to $4023/mo.
You're right I totally forgot about insurance. Oops. Sure let's use $150/mo, but IIRC that's more than I pay on mine. Maybe because I'm in a big building and the HOA has insurance for parts that I'd need to insure if it were a single family home? But I didn't factor in HOA, so $150's fair, even cheap.
$3482+$541+$150 = $4173/mo.
I still think this median household is going to have something like $4-5k/mo left over after principal, interest, property tax, insurance, and income tax. That's the most important number to get right in terms of how accessible this is. It tells us how much to they have to squeeze on everything else to make it work.
[1] https://smartasset.com/taxes/california-property-tax-calcula...
... also "$4556... representing one trip to Disney world’s worth of extra spending over the year." Holy shit really? I never would have guessed disney world is that expensive. Daaaaamn. Guess I'm never going there :(
(on second thought, I think you're right about the property tax estimate being low. I pay more than the online calculator said and my place is assessed below $1M. Maybe it's all the other stuff tacked on in SF? Add maybe ~$200/mo to my above estimate, we're still talking about something like $4k/mo left over)