I think this speaks to the difficulty in adjusting for inflation over such a long period of time.
I have no dog in the race, personally, but historians routinely put Rockefeller up as the top or among the top richest Americans in history. I do disagree with your assertion that GDP is invalid. You could indeed move to Tuvalu, and you'd be the richest person in Tuvalu by fraction of Tuvalu's GDP. Unless Bill Gates also moves there.
I have no dog in the race, personally, but historians routinely put Rockefeller up as the top or among the top richest Americans in history. I do disagree with your assertion that GDP is invalid. You could indeed move to Tuvalu, and you'd be the richest person in Tuvalu by fraction of Tuvalu's GDP. Unless Bill Gates also moves there.