The article speculates it may have been wealth from bitcoins combined with a thirst for power:

Mr. Chesebro’s 2014 investment in Bitcoin netted him “several million dollars,” he wrote in an email to Mr. Tribe that was quoted in a recent article in Air Mail. His marriage ended, and Mr. Chesebro acquired expensive homes in Boston and Manhattan, and a villa in Puerto Rico.
Soon after Mr. Chesebro’s big payday, his name began appearing on legal briefs filed by far-right conservatives, including John Eastman and a former Wisconsin judge, James Troupis. All three were described as co-conspirators in the federal indictment for the 2020 election scheme. He made hefty campaign donations to far-right Republicans, maxing out to Mr. Trump in 2020.