They won't. Sorry. They won't.
Let's examine the phrase "social media". Media, means collectively, the means of electronic communication. (Remember that word "communication"). Social, in a nutshell, centers on communication...the word relates to interaction with one another. (Remember: "interaction").
So, let's interactively communicate.
When that advisor, or friend, or webinar on book promotion told you to go forth and Tweet, Facebook, post blogs, etc., they meant for you to interact with those communities. Interact: behave with reciprocation.
Some of you "fail" to understand social media or interactive communication. You simply post links to your book or to your book's positive reviews over, and over, and over again. You do not interact. You do not communicate you do not reciprocate in communicating with the Twitter, Facebook, etc. communities.
I've purchased many books as a result from Twitter because authors interacted with me. I own all of Tasha Alexander's books because she and I communicated with one another. I started reading James Rollins for the same reason - even though I never would normally read his writings (and I love him). Cyndi Tefft convinced me to try her books because I find her interesting. I admire Courtney Milan on Twitter and applaud her fight for the rights of writers, so I own a vast majority of her books.
If all you do is tweet links about your books, how will I know you're interesting? How will I invest in you?
So. From this point forward, please, I implore you: practice interactive communication.
Thank you for listening.