One thing that differentiates great business leaders is their ability to negotiate deals. Almost universally, they have a well thought out plan based on extensive data gathering before they even begin negotiations. They are also highly observant of body language and behavior during a negotiation because those two thing tell them a great deal about someone and the status of the negotiation.
During negotiations, they have a distinct ability to detach themselves from events that might otherwise cause them to get angry or flustered. That ability makes it nearly impossible to manipulate them emotionally. By contrast, most people let their emotions rule when faced with any negotiation, and as a result, are quickly crushed by a more skilled opponent.