> Twist do you think happens to every city that has reached 16 million people?

It's not about the exact number, it's that one city is not going to 10x in population from getting the price of housing down to "still a city but not skyrocketing".

> I’m confused on why you think paris is affordable

Compared to San Diego, it does seem to be significantly more affordable, and mainly because of rent.

> and San Diego metro could somehow have enough water

The most expensive source of water, desalination, should be under $1 per day per person. And there's probably better options.

> to grow to 220 million.

That number is a silly number to explain density, not a proposal.

> and if you think that those cities are affordable…

No, the only comparison point was Paris, and the density of Paris.