“ The consequentialist argument for that heuristic is fairly straightforward, and it is e.g. the same as the basic argument against for-profit prisons†: if you can get something out of someone else's bad situation, you have an incentive to cause them to be in a bad situation. If you make money out of prisons being full, then you have a reason to lobby for higher imprisonment rates.”

Another approach: let’s say you have life-saving medicine, and you’re capable of selling it at a relatively low price without harming yourself.* If you sell it at a high price, people will still buy it, because spending is better than dying. However, they won’t have much money left over for anything else, and that will significantly decrease their utility. Selling the medicine is better than hoarding it, but it would still be even better to sell at the lower price, sacrificing a little of your utility to preserve a lot of the buyer’s utility.

*Whether this is actually true gets into complicated arguments about the economics of medical research.