wbernys we could also approach the question from the opposite direction: "what causes people to make imprudent choices?" Off the top of my head, I would say there's an easy problem and a harder problem.
The easy problem involves people who make choices based on empty opinion or pursuit of unnatural desires. In those cases, the answer seems simple: they have not acquired knowledge (nature, tetrapharmakon) and thus are driven by false assumptions or dispositions untempered by wisdom.
The harder problem involves the category of "natural but unnecessary," as there seems to be no fixed rule and prudent action depends on correct operation of the hedonic calculus. But (to echo Cassius's point) how do we learn to calculate correctly? Might it require obtaining sufficient data, in the form of pleasurable and painful experiences, until we are able to arrive at general guidelines?