Not sure if I agree with that, a highly skilled investor can generate high returns, that could match or beat a trader.
Traders claiming to get super high returns are often using leveraged instruments, if you factor in using leverage in an investment operation, If that operation goes well the returns will be quite remarkable.
let me give you an example, say an investor has $20,000 to invest. and he wants to leverage his position over two stocks he is comfortable with, we will use 2 stocks I have been involved with in the last 3 years CBA and CZZ (capilano honey).
Say he takes the full $20,000 puts it into CBA 3years ago at $45 / share, he then uses the CBA as collateral on a margin loan and puts $16,000 into Capilano, the CBA dividend more than covers the interest.
After 3 years his CBA has doubled to $92.00 / share, and capilano has gone from $2 to $9.20 + capilano dividends.
CBA- $40,000
CZZ- $73,600
total- $113,000
that's a 565% return in three years and that's not including the surplus dividends and franking credits, on a basic set and forget leveraged investment operation. He could have also built in a few option positions along the way to increase this return also.
Also this positions profits were not taxable along the way until he sells, and when he does sell, he gets a 50% capital gains tax discount.
It was previously mentioned by some (including yourself) that the average investor would be better off just going in an index fund so I think for the purposes of the above comparison you would need to use index returns rather than that of CBA and CZZ.
I'm not necessarily disagreeing with anything you have said, but based on the "average" investor, market returns seem more appropriate.
Of course when you start using a "Highly Skilled Investor" as a benchmark the sky is going to be the limit, as with a "Highly Skilled Trader"