Consider this scenario: you've taken a job but don't love it.
Your new employer offers you $1,000 if you resign on the spot. An excerpt from the Portfolio article:
The operating assumption is that anyone willing to take the company up on the offer lacks the commitment to the job and conformity to the culture that are necessary for a successful relationship. By Zappos' calculation, that $1,000 is less than the cost of keeping an uninspired call-center employee on the payroll.