Second Life is a virtual world with many participants created by Linden Labs. The currency used in the virtual world, Linden dollars, can be exchanged for real currency in a fully supported way. The exchange rate is something on the order of 270 L$ for 1 USD$. If you could exploit another player s client, you could potentially cash out their real money. The exploit may be something that another avatar whispers to you or an object they hand you or it may be a particular place in the world.
Source: https://threatpost.com/owning-virtual-worlds-fun-and-profit-081810/74344/