An incentive isn't an incentive if d/dx = 0 for behaviour x. Salary is how you get someone to work for you instead of a competitor, and keep them from spending

An incentive isn't an incentive if d/dx = 0 for behaviour x. Salary is how you get someone to work for you instead of a competitor, and keep them from spending their time worrying about mortgages, but it's not really an incentive unless someone is at risk of being fired. Performance bonuses, stock options, recognition, raises, promotions, and interesting projects are incentives.