Don't sell yourself, or your personal information, short.
"We've become a society used to the idea of giving up some amount of privacy in exchange for a service or discount. We understand that free services like Facebook have a catch that involves exchanging our personal details for something in return, in this case, a platform that enables us to connect with anyone and everyone. That clearly seems like a fair exchange to millions. This is nothing new. We've been selling our privacy for a while now..."