Investment professionals charge a fee (the tax you mention) because, in theory, they are at least that much better than the layperson investing. This hasn't always been true, and many active managers have been shown to be no better
at generating returns than the market.
There are other objectives for investors than just total return, like risk management, that justify fees in many cases.
> Bottom line: in making markets more efficient, the financial industry makes the economy as a whole a lot less efficient by siphoning off a huge chunk to feed itself.
That's a huge leap that absolutely requires some evidence to back up. This is the typical argument, but it's not convincing without any data, and just plays to the emotional "finance is evil" crowd.