Any number of people believe that promiscuity comes from low self-esteem. This explanation does not pass the muster of history. The Baby Boom generation and the Flapper generation did not suffer more than other generations from shortage of self-esteem, and many people in these generations were promiscuous. And the World War II and X generation had as many people with low self-esteem as anyone else - in case of the X generation, probably more than most other generations - and neither generation was promiscuous.
For most of their history, Christianity and Islam preached that self-esteem was a sin; and neither of these populations was promiscuous. Whereas the Pacific Islander cultures and the pagans did not preach that self-esteem was a sin, and sex was celebrated in these populations.
What all this means is that, in a historical context, there is no apparent correlation between self-esteem and promiscuity, and for that reason the explanation that promiscuity is a result of low self-esteem is false.
What actually does cause promiscuity? Some people are simply horny. Some people like the pleasure that they get. Some people think that that's what they have to offer. Some people experience intimacy and closeness. Some people like the praise and attention. Some people want to have fun. Some people are either not ready for or afraid of commitment. And then of course there are people who do it to survive.
Do some of these people have low self-esteem? Assuredly; but that does not mean that it is the root of promiscuous behavior as such. If it had been, then we would not be seeing baby boomers be more promiscuous than Generation X. Nor would we be seeing Christians and Muslims, that for most of their history demonized self-esteem, be less promiscuous than populations that celebrate it. There would be more promiscuity in Afghanistan or Alabama than in California, when of course the opposite is the case.
Promiscuity can have any number of reasons, but what cannot be said is that it is universally a product of low self-esteem. That is inconsistent with historical fact. There can be any number of reasons why someone - or a population - would be promiscuous. It is important to see each situation for what it is instead of forcing a blanket explanation on everyone.