No, the aggregate isn't important: the thought experiment is the same as if everybody earned $251k and spend $1k on rent -- but the percentage of income spend on rent would be radically different. But yes, if everybody suddenly had $250k disposable income, prices would be higher.

I think the point GP is trying to make, is that it matters more if you can afford in absolute dollars to have a family on whatever is left when you're done paying rent, not what the percentage is.

And my point is that an “everything else being equal” argument about the income and spending of an individual is not particularly useful when discussing demographic issues.

Yes, the cost of things is more expensive in dense cities, but by 2x-3x for some services and not at all for buying a pair of jeans from a retailer - those prices are pretty much uniform everywhere, modulo state/local taxes. I'll argue that one's quality of life is better in SV on $250k vs $70k in the rural midwest or $100k in a midwestern city - obviously this will depend on spending patterns, which depends on personal preferences. But for me, it's a conscious decision to make more and spend more on a west coast city.

The problem is you need more space after having kids. If your already spending 75% of your income on rent adding another room is not feasible.

Or more basically you need a significant surplus to be able to afford kids.

That entirely depends on the income level you're talking, which is the OP's point. If you're making $10 mil and spending $7.5 mil on housing, you probably already have enough rooms to have kids. And even if you didn't, you could surely find room in your remaining $2.5 mil to add a room onto your house or find a slightly bigger place. This obviously does not apply if you're making $50k... Hence why absolutes are relevant.

You are assuming that 7.5 million buys a multi room home. At the extreme it may only rent you a 350 square foot apartment.

Some people might spend 75% of their income on massive dwellings, but most people downsize if possible before going past 55% of income. And as we are talking about things on the social not individual level those preferences matter.

I guess his point is that what is important is the amount of money that is left after paying rent that you can use to raise kids (at least in this context). An homeless person spends 0% of his income in rent, but he's not in a good position to raise kids

What baddox's comment (about only the difference mattering) misses is this: what if you need another bedroom?

In other words, it's ignoring the fact that houses come in many sizes. Anyone spending 75% of income on housing has an enormous incentive to choose a slightly smaller apartment. And is completely unable to contemplate expanding slightly. What if you want two kids... and the second one turns out to be twins? Can their grandmother come to stay for the summer & help out?

If you're spending 20% of income on housing, then you have a lot more room to solve these problems. (And, as others pointed out, to get a different job which pays slightly less, etc.)

Me and my sister shared a bedroom in a two bedroom apartment for a few years. I recentlty had neighbors that had a one bedroom with two kids. I'm not sure where this requirement of one bedroom per child comes from. Really, that's just a luxury.

> I'm not sure where this requirement of one bedroom per child comes from. Really, that's just a luxury

Relavent

https://www.npr.org/templates/story/story.php?storyId=552528...

> The average American house size has more than doubled since the 1950s; it now stands at 2,349 square feet.

> Back in the 1950s and '60s, people thought it was normal for a family to have one bathroom, or for two or three growing boys to share a bedroom. Well-off people summered in tiny beach cottages on Cape Cod or off the coast of California

Indeed, I make no claim about the size of house you ought to be able to afford.

But families always have more need of space than the childless. This makes anyone contemplating children very sensitive to questions like "how much of my present after-rent income must I give up for another 100 sq ft?". And this will be very different for the guy who's found himself spending 75% (to be near google, or whatever) and the guy spending 20% (in 1958).