How many people are using social networks/media to promote their business?

Good day to you,

I'm interested in knowing how many people are using social networks/media to promote and expand their business(es).

There are a many myths and concerns about the security (or lack of) in the social networks and i'd like to create more education and awareness on this fast growing area of our technology/collaboration future. As a subject matter expert in this area of technology i'd like to help you overcome these fears.

Believe me, I deal with this everyday where people swear by the fact that social networks are riddled with these security issues and so they will never be a part of any of them.

If yes, which?

If not, why?