There's nothing wrong with trying to maximize your earning in doing what you do. If you want to have the greatest good on the world, you do what Zuckerberg does: make a shit ton of money and then give it all away to the best charities or greatest need (or at least plan to).

It's not a case of greed winning over good will. The number of entrepreneurs and businesses doing good in the world isn't limited by the will to do so - I'm sure you can find countless wannabee business and entrepreuneurs trying to make a positive impact. The limiting factors are barriers to entry: legal, political and marketing.

The greatest problems of our times aren't technical: they're political and legal.