Robert Morris was a great man, but he didn’t lose his fortune supporting the revolution. He lost it in land speculation well after the revolution. He reminds me of Warren Buffet’s witticism that only the three L’s can ruin a good man: ladies, liquor, or leverage. In Morris’s case it was leverage. Morris also reminds me of P.T. Barnum, who made a fortune on Jenny Lind’s concerts (Hollywood, as usual lied), and then lost everything investing too much in a clock company in Connecticut.
While he may not have gone completely bankrupt until after the war, he spent the majority of his fortune financing the war, providing the actual weapons of war needed to fight. There was no one paying any taxes at the time so he PERSONALLY funded the war for years. He almost certainly could have been one of our first Presidents had he been interested, although by then he had already lost his status as the richest man in America by far.
https://www.battlefields.org/learn/articles/robert-morris-financier-american-revolution
By 1780, the American economy was near default, and the paper money that had been printed, known as Continentals, were worthless due to inflation. Without Congress able to pay for the needs of the war, foreign diplomats had to convince friendly European governments to loan them hard coin and gold.
In 1781, with the situation remaining in peril, Morris began bankrolling the needed supplies of the Continental army on his own.
The American army began receiving the supplies it needed, and for the next three years, Robert Morris personally financed the American Revolution out of his own pocket. “Morris notes” became widely circulated promissory notes within the ranks of the army.