I just finished listening to Zig's "Secrets of Closing the Sale" two times through in a row. It was great. One of Zig's main points is that a good salesman has empathy for his prospect and is there to solve the prospect's problem. Echoing Rabbi Lapin's point about profit, Zig says something to the effect that you will get what you want only after you help lots of other people get what they want.
That sounds about right to me. In my experience, I've known lots of people who have done well in their careers through empathy and kindness. I've known a few who have been utter jerks. For the most part, though, jerks go nowhere because they rapidly burn through their professional and customer relationships.