Esav made money.  Lost of it.  He married into the tribe of Seir, and they were loaded.
One of the princess of Seir was a lady named Meheitavel the daughter of Mei-Zahav.

Rashi says, how did her family get the name Mei-Zahav?  It means, “What’s gold?”  As if to say, gold was nothing in their eyes.
(Others suggest that ‘Mei’ is from the word ‘water’ as if to say that gold was like water in their house.)

Seir made their money in a few different ways.  The Torah tells us two of them.  One was from the Hori family.  Rashi says that the Hori family were value investors.  They could spot an undervalued plot of land that nobody else could cultivate and they had this amazing talent where they could taste the soil and discover what type of crops would prosper there.

Another stream of income came from Anah.  “He was the same Anah who discovered mules in the desert when pasturing the donkeys of his father Zibeon.”

Rashi says that he bread donkeys and horses.  The product was a super fierce animal with the strength of a horse and the versatility of a donkey.  He was the Caterpillar of his day, selling the best farming tractors and farming equipment.
The problem was, his genetically engineered mules did not reproduce.  Which really wasn’t a problem for Anah.  It meant that every few years you had to come back to him and buy a new mule.  So they were also the Monsanto of their day.

I thought of this Rashi about the mules when I read Isaac Asimov’s Foundation series.  The arch villain went by the name The Mule.  Throughout the book it is assumed that he went by this name because he was incredibly powerful.  As Rashi says, “mules were called ‘Yeimim’ because fear of them lies on all creations.”  But at the end of the Foundation and Empire (spoiler) The Mule tells us that he chose the name not because of his might, but because he was only interested in destruction and had no intention of having children and establishing a dynasty for himself.

Asimov grew up in a religious Jewish home, and I have no doubt that he learned this Rashi as a boy and it made a deep impression on him.

The person who purchases a mule invests in today at the expense of tomorrow.  The person who buys a donkey sacrifices a little bit of strength today, but he has an investment in an animal that can reproduce and the fruits of the investment can potentially provide for the future.

Esav shared this quality of the mule.  From the very beginning he was willing to sell the legacy of his future children for a bowl of soup.  He took the money of Seir and built his nation which waxed strong for a time, but then waned into obscurity.  Yaakov took the longer harder road, but his legacy exists until today.