https://en.m.wikipedia.org/wiki/List_of_most_expensive_citie...
https://www.atlasandboots.com/remote-jobs/most-expensive-cit...
Day-to-day expenses are a tiny part of a typical budget. In most scenarios, housing, income taxes and transportation alone will easily cost you twice as much in SF compared to Zürich.
As a software engineer, the salary difference should make up for it, or even reach levels that are unlikely in Switzerland. That's great, but for most people, I can guarantee you, Zürich is a lot cheaper.
The point is that many things, including many things that “rich foreigners” use to do, are more expensive in Zurich than in San Francisco. For example [1] a hair cut is twice as much ($62 vs $30), a basic dinner at a neighborhood pub for two is 50% more ($74 vs $50), going to the cinema is 30% more ($18 vs $14), a gym membership is 30% more ($118 vs 91$), etc.
[1] https://www.finews.ch/images/download/Mapping.the.worlds.pri...
edit: in the linked document, monthly rent for a mid-range 2-bedroom apartment is 37% higher in San Francisco ($3449 vs $2520). However, the cost of transportation in its different forms is higher in Zurich.
SF and NYC are a lot more expensive.
You're right about the size of the job market though, it's tiny, even relative to the population size.