Thales of Miletus was often mocked for being poor. Some said that this proved his philosophy was useless. But while studying the stars one winter, Thales discovered that it would be particularly good weather that season for olives. He subsequently leased all the olive presses he could. Both in his home town of Miletus but also on Chios island. The lease was cheap. No one else made a bid. Many months later, the time to harvest came. It was indeed a great year, so they all needed oil presses. Since their need was urgent and Thales controlled all the presses, he increased the price for his services and made a lot of money.
This was how he showed everyone that if a philosopher sets his mind to it, he can indeed make money. But he chooses not to.
Politics – Aristotle