Franklin donated a small amount of money which grew to a very small fraction of the economy for a time period less than 1/60th of the proposal; he got incredibly lucky that he did it in America, and not in any of the other growing powers or economies of his day or later, such as Russia/France/Germany/Mexico/Argentina/Japan, which might have wiped out his legacy; and even Americans have found it difficult to replicate his feat.
Franklin donated a small amount of money which grew to a very small fraction of the economy for a time period less than 1/60th of the proposal; he got incredibly lucky that he did it in America, and not in any of the other growing powers or economies of his day or later, such as Russia/France/Germany/Mexico/Argentina/Japan, which might have wiped out his legacy; and even Americans have found it difficult to replicate his feat.