Why didn't Eli Whitney make money from the cotton gin?

Eli Whitney didn't make significant money from the cotton gin because he was unable to secure a patent that effectively protected his invention. Although he was granted a patent in 1794, it was difficult to enforce, and many manufacturers produced their own versions of the cotton gin without paying him. Additionally, Whitney's focus on producing firearms with interchangeable parts diverted his attention from capitalizing on the cotton gin's potential. Consequently, while the cotton gin revolutionized the cotton industry, Whitney's financial gains from it were minimal.