maybe if one has a primary goal of paying off the loan in full by year twenty, repaying as much as possible each month is vastly superior to investing: it gives us a slim 3 % risk of not reaching our goal, compared to 23 %.

if one does not mind being in debt and wants a high-risk investment strategy for this money8, then investing it is better than paying off the debt: the inverse Russian roulette case is nearly 3× higher with that strategy.

If one cares about the median outcome9 then it doesn’t matter all that much which of these strategies one chooses, and the optimal may well be a combination.