"Odd numbers are prime" IMO, although there's room for disagreement there.
Most people would automatically read "ducks lay eggs" as referring to a strict subset of ducks, but I don't think "smokers know the health effects of smoking" would automatically be read as referring to only a strict subset of smokers.
It's true that "smokers know the health effects of smoking" wouldn't be interpreted as rigidly as the mathematical statement "Odd numbers are prime", but I doubt it'd be interpreted as loosely as "almost all smokers know the most famous health effect of smoking, and most of them know some of the less famous ones" either.
(There's at least one way to interpret "smokers know the health effects of smoking" a bit less literally than I did: if smokers knew the total health risk they ran by smoking, one could reasonably assert that smokers were fully informed for the purpose of deciding to smoke, even if they couldn't name every individual health effect, or every effect's individual magnitude.)
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).