Current GDP is about 25 trillion. 1% of that is 250 billion. Current wealth accumulation, richest person.
Currently Bernard Arnault has about 211 billion. I expect wealth accumulation at the top to proceed faster than overall GDP growth, so I think this is quite likely.

@FedorBeets the Rothschild were trillionaire in their time. There is no tendency for the rich to become more important, the only factor is inflation so of we ignore capitalism collapsing it would take 2050 or so.

@DuSusisu Why would inflation matter? Shouldn't that impact the greatest person's wealth as well as the american GDP by about equal effect?