Eli Whitney earned almost nothing from the cotton gin because its simple design was easily pirated.

Eli Whitney received his patent for the cotton gin on March 14, 1794, but the simplicity of the machine proved to be its commercial downfall. The device used a wooden drum with hooks that pulled cotton fibers through a mesh, leaving the seeds behind. Because any local blacksmith could replicate the design, illegal copies spread across the Southern United States within months of its debut.Whitney and Phineas Miller initially attempted to operate as a monopoly by processing cotton for farmers in exchange for 33% of the total yield. This high cost incentivized plantation owners to build their own gins and claim they were original inventions. The legal system at the time was also ill-equipped to handle patent disputes, and local juries often sided with their neighbors rather than the inventor.By the time the Patent Act of 1793 was strengthened in 1800, the market was already saturated with pirated machines. Whitney famously wrote that an invention can be so valuable as to be worthless to the inventor. He eventually abandoned the cotton gin business and secured a government contract in 1798 to produce 10,000 muskets.This new venture was far more successful because Whitney pioneered the use of interchangeable parts. This manufacturing shift laid the groundwork for the American System of manufacturing and the Industrial Revolution. While the cotton gin transformed the global economy and increased the demand for enslaved labor, Whitney himself only became wealthy through his contributions to the arms industry.