A dictator running a country that has a large supply of natural resources can profit even if he horribly mistreats his people. Normally if a dictator shoots, starves and uneducates his citizens, then his nation's economy will crash and the dictator won't be able to extract much wealth from it. But natural resources change this. For example, if a dictator's country contains huge oil reserves he can bring in foreigners to extract and sell this oil. The dictator, in this case, can become rich without help from any of his citizens and so the dictator can freely mistreat his people and still turn his power into plentiful profit.
Similarly, most employers can't horribly mistreat their workers and still expect their workers to do productive stuff. So even if an employer wants and is able to exploit his workers to the maximum degree, he still has some incentives to treat his workers well so they can produce wealth for him.
But a young pretty prostitute is, in a sense, a "natural resource" for a pimp. Even if she is mistreated to the point where she can do no productive (non-sex) work, she can still make her pimp much money. Profit, therefore, doesn't necessarily constrain the cruelty of pimps and resource-rich dictators.