Replacing large swaths on single story single family houses with multiparty rentals does not necessarily involve any high rise buildings. Paris and Barcelona have proven that very high density can be achieved with four to six stories or less.
I have only vague idea about Barcelona - quick check shows like it may be on the scale of E5K per square meter (it was $100K per 2-3 bdrm 20 years ago, so 3x-4x today seems reasonable) So you need to have like at least $60K salary - do they have that there?
Again, i'm not against high[er] density. I'm against it being suggested as the panacea for housing affordability crisis - as far as i see it looks like it may even worsen the crisis (at least for some less fortunate people - like relatively affordable low income communities being displaced by upscale new construction like we have happening everywhere in SV).
Please just show where higher density did help to alleviate the affordability crisis. I think even the massively empty apartments in all these massively constructed ghost towers in China aren't falling in prices.
However, if the prices in silicon valley were, say, 30% lower than they are now due to zoning which allowed more housing, would that constitute as evidence? You could still say that the "prices are high, higher density housing doesn't work!" - even if the higher density housing would've decreased prices by non-trivial amounts.
In any case, it's weird to see people objecting to basic supply and demand when it comes to housing.