I don’t think you can assume this to be the case, especially outside of the Bay Area.
My first startup was one where I was hired because I was young and cheap. I could be paid in free lunches rather than 401k matching and decent healthcare plans.
Big companies often pay better salaries.
There are plenty of people who would consider themselves extremely lucky to work at a startup, even for cheap. I know many older people working much worse jobs. I think it's fair to assume that most startup workers have other options, and that generally those options are worse.