Monkeys for sale? How much is a monkey?

Why do people look after pets? Especially the wild ones? I know some people have snakes, spiders, monkeys, even tigers... And you know guys, wild pets worth a treasure. An ordinay monkey costs at least 2 thousand dollars.
Furthermore, I don't recommend anyone to keep such dangerous animals at home. They are sometimes very dangerous. Look.

The monkey pissing on a man