Default how can social media be helpful? FB G+ Twitter Instagram

Hello every one,
I wanted to ask how can social media be good to internet marketing. my thought is creating a fan page with a subject that interest people on Facebook, what if i reach thousand of likes and re post, how can i benefit from that?
As far as the other social media like i mentioned their names, Is there the same potential as the others in generating income or each one is different.

See original post by smmpoint