Very interesting. This is a template for great story material based on deep ethical and moral questions. Weaving this stuff in to flash out characters will be intriguing. Thanks. (I'll most likely accept this answer, but I want to wait the standart 48 hours.)

@TheDyingOfLight Thanks. You definitely should wait. While I wrote this wall of text hoping it would be relevant and useful to you, it strictly speaking is not that good an answer to your actual question. I mostly talk about other things related to the question. And give zero actual numbers.

The Culture (series) goes into this a bit with the book...Surface Detail. The Culture doesn't have any laws at all and the main character keeps trying to ask one of the drones how that even works. The short answer being, "you'd get a slap drone assigned to you and it would kill your social life. So....don't be a jerk?"

@Draco18s The Culture is actually an extreme example of what I was trying to explain. The AIs that manage the Culture have almost absolute ability to prevent anything the humans do from becoming a threat. They do not need specific deterrent for anything. So they do not need to criminalize things in advance. So the Culture might be almost entirely crime free. The fact that the AIs would obviously be able respond to any crimes effectively and that everyone knows that mean that only mentally unstable people would even try to commit crimes. And the AIs can detect mental instability.

We have (if you're in the US) a pretty good example of criminal relativism right now. If I happen to want some marijuana, I can just drive down the road a couple of miles and buy it from the store & greenhouse that grows it. If I lived in a different state, that would expose me to the chance of a jail sentence, and the cops would raid the greenhouse & brag about seizing (vastly inflated) $X worth of illegal drugs...

The point about VR hacking is especially apropos. Without going into any sort of theological or psychological arguments, we'll just say that it is part of human nature to rebel against governance. Most people will control that urge, but there will always be some that won't, i.e. some people will "need" to engage in illegal activities, no matter what those activities are. Invasion of others' lives, whatever form, is a sort of crime that is likely to continue to occur regardless of economic circumstances.

+1. For possible future crimes you can also try to extrapolate from current changes in legislation due to social media platforms. At the beginnings of internet, only things which were sort of "hard crime" (advertising illegal activities or selling illegal things) were taken notice of online. Nowadays, as far as I understand, you could face charges for many more things done online.

-1 for false statements on polygamy. Reasons to forbid it are still real: "That link is far from obvious, but actually quite simple. If the richest and most powerful 10% of men have, say, four wives each, the bottom 30% cannot marry. In many societies that means they have no status, are not considered adults and perhaps are barred from having sex. Frustrated and humiliated, they often take desperate measures to become rich or powerful enough to reproduce. Such as taking up arms and looting the village next door." bit.ly/2DwUWN5

@Mołot Thanks for the explain. Interesting but it does not actually have anything to do with this answer or the historical reasons why polygamy is illegal. Also that is not an actual study that proves anything. (cont->)

@VilleNiemi "it does not actually have anything to do with this answer" - but it does, as your answer states that reasons to forbid polygamy are no longer valid, when one of the major ones is still valid, and probably will be valid in the future. I explained my downvote. You may edit your question to remove false statements, and I'll remove downvote. Or you may leave it, and I'll leave my vote. And that's it, arguing will not be productive so that's all from me on this topic.

@Mołot While I believe the correlation, causation is bit of stretch. Honestly given that the most obvious reason for increased polygamy in a society would large wealth disparity and wide spread poverty and that my second guess would be social insecurity, there really is no need to assume that polygamy causes unrest, IMHO. The problem is not that lack of women makes angry young men restless. It is that same reasons that push polygamy also create large numbers of angry young men in the first place.

@Mołot No, the ban is from the early middle ages, they did not have this issue because very few people could afford polygamy and large portion of population could not afford to get married. So this issue cannot have been relevant to polygamy being banned.

@Mołot I was going to edit to clarify but my statement actually is quite clear already that I was referring to the original historical reasons that I explain in the paragraph. Maybe I should add an explicit statement that other reasons might exist? But that seems kind of silly because other reasons are obviously always possible...

Disagree with the analysis of “why people commit crimes”, which is founded in the belief that all crimes are rationally committed for gain. What about cases where the criminal is mentally unstable (whatever that means)? Eg, is suffering from paranoid delusions and believes he/she must murder random innocents? Or deliberate crimes of passion?

@eggyal The reason it was irrelevant is because the question is about the effect of post-scarcity on the statistical crime rate. And my answer was that it should not matter that much. While "irrational crimes" are still part of the statistic they do not have a relationship with post-scarcity that is separate from the general economic effects. People probably will get better mental health care, maybe much better, but that is just a part of the economic effects not a separate issue to cover. And with my answer being that that none of that really matters...

@eggyal Edited in a short clarification. It really was needlessly misleading. Hope it helps. Thanks for giving a helpful comment!

@Molot What if each of the four women is intimate with four men? Not to mention LGBT.

@Mołot, polygamy is somewhat tolerated in Israel, but it is something usually confined to relatively poor and less educated people. I am quite sure that if you check Arab countries in which it is even less restricted that you will find that it causes no real social issues

@Mołot To add to what you said (and I agree) this can be an issue for even top 1% of men. Every man takes 4 wives each out of a 50/50mf population, that alone is enough to offset balance to be noticeable in the population and cause issues (49 vs 46 is 6% more men than women, 3% of US 325 million, that's 9,750,000 people). I also want to mention that the economic issues are still real as well. What happens with health insurance, what happens with inheritance, dependents, divorce etc... there are a lot of economic questions that become extremely complicated with poly marriage.

@Molot and for a thought experiment we can do top 2% and 3% as well, 48/42 (14% more men) 19.5 million and 47/38 (23% more men) 29.25 million. Heaven forbid you applied this to a much larger country or the whole world, in China with more than 4x the population of the US, 29.25 million turns into 117 million people. Polygamous societies sent the men to war/through life threatening trials/find ways to push them out to keep men/women ratio low. Masai circumcise their young at 12, push them out if they show "weakness", and then send them out into the wilderness for many months to survive.