I suspect the key to making money off the poor is buying from them low, rather than selling to them high. In other words...sweatshops. Pimps. Mechanical Turk.
These are all distasteful, but what makes them unsuitable for the task of Helping Humanity is that these transactions are really bad transactions to be making, for reasons the financials don't show. A 3rd-year developer is worth more than a 1st-year developer---is a 3rd-year sweatshop laborer worth meaningfully more than a 1st-year sweatshop laborer?
These are all distasteful, but what makes them unsuitable for the task of Helping Humanity is that these transactions are really bad transactions to be making, for reasons the financials don't show. A 3rd-year developer is worth more than a 1st-year developer---is a 3rd-year sweatshop laborer worth meaningfully more than a 1st-year sweatshop laborer?