By this logic, every commodity should only ever be sold at cost. Or, better, for free! Any price higher obviously means some poor person somewhere can't get as much as they need.

Now, this is obviously a silly hypothetical. Very few people are going to produce sheet metal for that poor chap if they can't cover their costs plus at least some profit, leading to nobody having any sheet metal. Now the whole world is worse off and lacking sheet metal, and for what?

Some things in the finance industry are valuable. Insurance and its ability to spread risks springs to mind readily. The joint stock company, and its ability to pool resources to grand ends, has unleashed incredible forces.