No matter how smart your mind is, you can’t outsmart human nature.

In 1720, Newton—the one who discovered gravity when an apple fell on his head—bought shares of the South Sea Company. In just a few months, his investment doubled. He was still rational enough to cash out while he was ahead, pocketing £7,000 (enough to buy a luxury house in London at the time) and exited gracefully.

But what happened next? After he left, the stock price kept soaring. Neighbors, servants—everyone around him seemed to be making money. Newton couldn’t sit still. Watching even “fools” profit, he, the genius, felt like an outsider.

We all know what happened after that—he jumped back in at the peak, bought more, and ended up losing everything. Newton himself lamented: “I can calculate the motions of heavenly bodies, but not the madness of people.”

Sound familiar? The market is always full of these cycles.