Amasa Stetson (1769-1844) comes to mind. He was the brother of a direct ancestor.
According to various secondary sources, Amasa started out as a poor boy, learned the shoemaker's trade (his father's line of work, and also a major part of the economy of his home town of Braintree, Massachusetts), and somehow got into the big-time shoe business in Boston together with a brother. He amassed a large fortune. At his death in 1844 his estate was worth about $500,000 -- in 1844 that was serious money! He married, but he had no children.
During the War of 1812, he was commissary for the district of Massachusetts. This apparently involved procuring supplies for the military. Some time after the war he successfully sued the U.S. federal government to pay him a large sum of money owed to him for helping to finance the war. More than 200 years later, I have to wonder whether he really had been a patriot using his own funds, or if he somehow increased his personal wealth at the expense of the government.
He built a town hall for Randolph, Massachusetts, and created an endowment fund for the town school. In 1801 he bought land in Maine and later caused the town to become the town of Stetson. He built a public meetinghouse for the town, with the intent of donating it to the town, but the transaction was not finalized. I learned about this from a 1997 newspaper advertisement in which the town was attempting to gain clear title to the property it had been using for over 150 years. The ad contained a long list of his heirs, apparently from around the time of his death, seeking to determine whether any of them or their heirs might want to dispute the town's claim to the property.
I have not found evidence of relatives in the Stetson family inheriting significant shares of Amasa's wealth, but I have observed that his surviving siblings and their children were generally rather well off.