Gottfried Leibniz was one of the smartest men of his age. And that says a lot considering he lived during the European Enlightenment. He was a master of mathematics, philosophy, and science, among other subjects.
He invented calculus, having defined its rules simultaneously with Newton but publishing nine years earlier (which is a good thing, otherwise we would be using Newton’s term for derivatives, fluxions).
His stepped reckoner was one of the earliest mechanical calculators. He developed binary arithmetic and mathematical formulations of formal logic. He was a forefather to the computing machines developed by Babbage and Lovelace in the 19th century.
His work was recognized by Euler as a precursor to the field of topology, developed centuries later.
As one of the great early modern rationalists he wrote extensively on subjects such as metaphysics, phycology, and theology.
According to Anthony Gottlieb’s The Dream of Enlightenment he had plenty of ideas for lesser known inventions as well. He designed improved watches, nails, submarines, and a fishing machine.
He also came up with an idea for spring loaded shoes, which presumably would let one escape from danger Wile E. Coyote style. Something he may have had a need for, given that his patrons were not always happy that he kept on getting distracted instead of finishing whatever they were paying him to do.
I guess the lesson is it’s perfectly ok to have stupid ideas. But also make sure you finish your real projects.