What legal ways do people make a profit that produce the largest net loss in utility?

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).