[erik_seaberg]

Or maybe I have all the customers because I can afford to sell at lower margins.

[em-bee]

sure, but if i don't pay a higher salary then i won't be able to poach the employees you just trained.

[HPsquared]

So you pay them a little more but less than the cost of training. Win-win (previous employer loses).

The same issue comes up any time a company makes an "investment" in their staff. The bigger the investment, the bigger the incentive to jump ship.