I used to joke that Bill Gates and I have an average net worth of $15b.

I thought basic statistics was misapplied here. Using one ultra-rich person in the NL as the example of the elite was not a big enough sample size. I would wager that the average net worth of the top 1% of Dutch people would be much less than the example given. This would reduce the GINI calculation by quite a bit. Using 10% would be even lower.