Here's what my family's spending looked like over the last 12 months:

      $8,824  housing
      $1,870  food
      $2,965  medical
      $8,982  personal and transit
     $55,306  savings
     $52,761  taxes
    $130,708  donations
    
    $261,416  total (income)

For most of this year it was me and my wife, with our first child being born 2/3 of the way through. This is with both of us working; let's imagine instead we had two kids, one $100k income, and one of us stayed home with the kids.

To adjust for there being about twice as many people, let's double the first four categories. And because we're talking about a $100k income let's decrease taxes proportionally down to $20k. Now tax rates are graduated so we would really pay less than that, and kids cost less than adults per person in terms of food and housing, but let's be conservative and stick with this. What do we get?

    $17,648  housing
     $3,740  food
     $5,930  medical
    $17,964  personal and transit
    $21,753  savings
    $20,000  taxes
    $10,000  donations

   $100,000  total (income)

When an $100k income can support four people with enough left over to donate 10% and save 22% then I feel pretty confident calling it "rich".

(This is Boston, which is not quite as expensive as the bay area, but nearly so.)

I'm friends with a married couple who's got one kid, planning on having more. Husband works in tech, wife doesn't work. Their finances end up looking a lot like mine, except they live in an area of Palo Alto where my rent gets them a decent-sized apartment. (Both I and they are saving for retirement.)

ok, so let's try to see how this works out

making $100k/household in Palo Alto:

$30k goes to taxes $30k goes to family housing, unless it's a trailer park probably about $10k goes/will go eventually to things like soccer, music, other misc kids stuff, unless you decide to punt on after-school development

the remaining $2.5k/month goes to food and clothing for 3 and I guess retirement savings? We also leave out cars, gas, vacations, cellphones, saving for college, etc etc.

There is not a chance to ever buy any housing in this area on that. I also don't see much room for more kids. Sounds like barely covering living expenses.

We live in a world where a lot of people are still living on $2 a day or less. And you consider $10k/year on soccer and music lessons a necessary living expense? Gimmie a break.