[beisner]

OP is making a dumb libertarian argument basically saying "there's nothing stopping people from doing what they want except the threat of force/violence" (which is trivially true, and the mechanism by which any group of people - even democratic societies - imposes their will on insiders or outsiders), and "do you really want to use THE THREAT OF VIOLENCE to prevent me from STARTING A BANK???" as if it's different from the enforcement of any law. OP questions the use of "should" uncharitably, because the original comment's unstated assumption is clear - society "should" be set up to tradeoff freedom and minimizing collective harm. Violence is not the only form of harm; unregulated banking can obviously cause harm in the society (starvation was pretty harmful in the US during the Great Depression), and so it's valid to question whether or not society should consider how the benefits of private banking (with any amount of regulation) trade off with a public alternative.