Other view on this: if you have a job as a SWE at Google, you might have had to relocate to a different country where you are not super well integrated (for example, only basic knowledge of the official language). Leaving your job might make you lose your visa, having to relocate and lose a large part of your social circle. Make that even more fun if you have a partner or kids or whatever.

Of course it's usually going to be somewhere in the middle. But not everyone lives in the Bay Area where you can hop between jobs and change employer every week.