Depends on what's being compared.

Being a billionaire is understood as having a net worth of $1 bi, so we ought to compare the net worth of the median someone at retirement. If that someone are Americans, that's $200k, so 5k times. If it's the world at large, that's roughly $10k,so 100k times. If we consider the billionaires at the top of the ladder, it surpasses 1M times.