The conclusions of the FT article are completely wrong. With fewer rich people around, chances are that legislation would be less frequently bought to benefit them at the cost of the country's overall prosperity.
What I'm saying is you may be defending billionaires when you mean to be defending a system you believe is optimal but still has the negative outcome of billionaires (not to imply the billionaires themselves are intrinsically bad as people but the concentration of wealth in their hands is).