Earlier quoted context omitted.
The money ears money thing is key. A wealth tax that equals the money you can earn from having money would prevent runaway inequality due to the "rich getting richer" effect. S&P 500 has a long term annualized return of 10%. If you have a 5% wealth tax on stock you have in S&P 500 then you are still earning 5% returns (well above long term average inflation) without actually lifting a finger.
Yeah but it causes the much worse 'government getting richer' effect.
On the contrary there are plenty of areas where we know governments are vastly more efficient than markets.