Not sure it's a useful question - whether it's financially profitable or not, harm is harm. Doing harm for political or personal reasons is no better than doing so for profit.
There's probably no industry that doesn't cause some harm. Certainly we can all agree that career politicians, teachers, and surgeons all get paid and cause harm to some.
So, if someone leaves food to rot in the fields, it of no concern whether there are institutional incentives that explain this action? We should just focus on the act itself, and not examine what forces produce it? And the issue is not whether some are harmed, but whether the total net effect is harmful.
This is an offshoot of a thread I made earlier, but which wasn't eliciting the sort of responses I'd hoped for.
So let me pose a clearer question with less potential to get people on watchlists.
What legal ways of making a profit are the most anti-altruistic, the most damaging to society, the opposite of effective altruism in result.
I am using utility loosely. The answers need not be given from a utilitarian perspective at all, but instead merely deal with any means of making a profit that seems to you clearly wretched, and such that the world would be better if nobody participated in it.
I'd also like to emphasize that these things should be legal. There are some obviously wretched illegal businesses that would top the list otherwise. If something is legal but only in a particular jurisdiction, then you should only discuss it within the context of the jurisdiction where it is legal.
If it's a grey area, go for it, but extra points for society-harming enterprises definitely legal in both the letter an the spirit of the law.
This is NOT about whether the enterprise in question should be illegal, just whether it causes a net loss of utility (deal with counterfactuals however you see fit).