As primarily an index investor, what I take from the article is revealed in this:
"...whereas for a professional underperforming an index equals 'career risk' and possible loss of livelihood."
Under-performing the index is death for an active manager. And the only way they have a chance of beating it is with more risk. Take the risk, roll the dice, and if you win, you get promoted, increase your income, and get more money to play with. If you under-perform or match the index, you loose either way. So there is a big incentive for them to gamble. The problem for the investor is that they are rolling the dice and gambling with your money.
Merrily, merrily, merrily, merrily,
Life is but a dream.