You can't fast-forward your net worth and leave everyone else's frozen in place. If 10M is the bottom of the top 1% now, In 20 years 10M won't be enough to be in the top 1%.
- Estate taxes: the government wants its pound o' flesh
- Squandering: the wealth is generally gone by the 2nd or 3rd generation. I remember this from The Millionaire Next Door (W. Danko), which is from the 90's, but I haven't come across anything to date stating that the trend has been reversed.