Eli Whitney - The really famous one

From Wikipedia:
"Eli Whitney (December 8, 1765 – January 8, 1825) was an American inventor best known as the inventor of the cotton gin. This was one of the key inventions of the industrial revolution and shaped the economy of the antebellum South.[1] Whitney's invention made short staple cotton into a profitable crop, which strengthened the economic foundation of slavery. Despite the social and economic impact of his invention, Whitney lost his profits in legal battles over patent infringement, closed his business, and nearly filed bankruptcy."
Poor Eli Whitney, the man who brought us guns with interchangeable parts, and made cotton into a cash crop was plagued by misfortune throughout his life (his lab was broken into and people copied his gin design, and one of his factories burnt down putting him in serious financial trouble). Then again, the whole facilitating large-scale commercial cotton kind of lead to slavery being viable. He also had shifty sweetheart weapons  contracts thanks to his Yale connections.  There is even evidence that his attempts to build a cotton gin were unsuccessful, and that his design flaws were solved by a woman named Katherine Green (source).