I guess you could argue that these are the only legitimate ways to make wealth or money. Technically, one can do high speed trading that essentially acts like computerized insider trading (and middle man economics). If someone provides no actual service, but still receives money, is that legitimate?
I don't think you could argue that. Finance encompasses a lot more than questionable trading practices. I said finance, and not say banking, since I meant any kind of banking and investing. And there is an equivalence between debt (loans, bonds) and equity ((yc,angel,VC) x investments, stock offerings) since from the perspective of the company, you are paying rents on capital in both cases.
Do I need to argue the importance of loans and efficient allocations of capital? If you don't like thinking about this with money, what about with loans of goods?