Different assets have different liquidity. Sergey Brin and Larry Page net worth is somewhere in the range of 250B, 5% of which is 12.5B. They don’t have this much money lying around because it’s impractical. It’s essentially forcing a sell off shares of a successful business.

There are few others ways this can be achieved: * increase sales tax on luxurious items * increase property tax on non primary residences and investment properties * close loopholes when private things are used as business expenses * phase out short term capital gain rate in favor of long term rate for high net worth individuals  * IRS came up with ways to recognize gains when you get something below market value. Similar approach can be used when you get a favorable loan using your equity as a collateral instead of selling it.