Oh, yeah, there's definitely a scale to it. A twitter customer service employee is paid much less than a software engineer... though even the latter isn't going to have been at "will never need more money in their life" levels, particularly given the American social safety net or lack thereof.
That said, I do find that people are fairly loyal to a company that treats them well.
Nobody has to be there to survive, everyone is there willingly because they saw it as the most advantageous place to work, and they'd switch to a different company tomorrow if they got the right offer. Loyalty is a term from a different era.