Schoenburg does nothing for his $200K/yr of investment income except pay fund managers.Presumably he also gets a salary for his day job.
His situation is not to be compared to that of those who actually WORK for hi incomes, like physicians, managers of hands-on highly technical operations, & the like. How often does Schoenburg get called at 1:00 AM to attend to something gone wrong? How many all-nighters did he pull to complete a project or see an emergency thru?
Taxing investment income at the same rate as wages/salaries would kill investment, as it would eat up the net return. If there's something wrong with taxing investment income at a lower rate than wages/salaries, then lower the wage/salary rate.