According to Piketty, rich people invest secretly into large mysterious companies. This pretty much precludes public markets, so they probably own lots of smaller businesses (e.g. hotels).

Why do you believe lending to farmers is a bad use for resources?

Investing in oil futures is transmitting information to the markets. It encourages current users to avoid unnecessary use of oil and produces to produce more. That's a valuable service.

What exactly do you think a hedge fund does?