This article reports results of a poll by the Pew Center on the States which shows that roughly 1 of 99 adult Americans is in prison. That sounds high upon first hearing. Then I did the following thought experiment and concluded it may be low.
I graduated from a small high school in a semi-rural area where all social classes attended the same school. In other words, residential segregation (which existed) did not result in kids of different social classes going to different high schools - there was only one. So, we had students whose fathers were bank presidents, doctors, dentists, CPAs, others from welfare homes, and everything in between. - the whole gamut. Our graduating classes, when I graduated 50 years ago, ran about 100 students.
Given that experience, I asked myself how many of my classmates should be behind bars and came up with a number larger than one, although smaller than five. Did I live in a particularly criminal area? On the contrary, my parents and I suspect most adults thought the area "a good place to raise kids."
Do we lock up some people who pose no direct threat to society? Sure. Most white-collar criminals are unlikely to mug you or steal your car. Can you think of another foolproof way to make them miserable without locking them up? If so, I'd bet your governor would like to know about it.
One reason we have so many people in prison is that several decades ago we mostly did away with our mental hospitals, places where we warehoused folks who could not function with or live around others. Many such dysfunctional people are now in prison. Would we be happier if we took care of them in 'hospitals' instead of prisons? I do know that would inflame civil libertarians.