Elon says work could become optional in 10 to 20 years. We already know what humans do when it is. They build harder. The FIRE community is the cleanest experiment we have. A 2018 TD Ameritrade study found that 75% of financially independent respondents said the "FI" mattered more than the "RE." Three-quarters of people who hit the goal of "you never have to work again" do not stop working. They start a company, write a book, take a lower-stress role, or join a nonprofit. Empower's 2023…