This is a blanket statement and obviously does not apply to many inmates. There are numerous categories of exceptions to this statement: wrongly convicted individuals; those who engaged in well conceived (non-impulsive & w/o malice) white collar crimes...embezzlers, inside traders (Martha Stewart & the Enron crew), etc.; career (non-impulsive) blue collar criminals who specially choose avenues with little or no violence due primarily to their temperament...car thieves, burglars, small-time drug dealers, etc.; and numerous other categories.

Not everyone in prison is a bad person, many just made poor decisions that cost them!
M.