There is a reason folks flock more to SF rather than to nowhere state. If you save 10%, it is still 20k saved compared to 8k. If you lose your job, there are 10 choices compared to one (or none), access to cutting edge of tech rather than reading about it on hacker news and so on.
You need to measure purchasing power using PPP rate, but even still NY and SF known to be expensive areas with high tax rates.
SF engineer could earn 200k year but this money could be much low as 80k in another state if you compare purchasing power.
It's complex. The Americans can always buy a car but never foods. This become a meme in my home country.
There are always trade offs.