ben wilson: How did the roschilds become the richest family in the world? That's why i started studying. So let's explain how they did it. Arbitrage is when you take advantage of price differentials to turn a profit. And that's what the raschals did. They e they used arbitrage. We'll get into some of the complexities. But i wanted to start off talking about this idea of arbitrage, because you have to understand it in order to understand how they were able to do what they did.