Recently I was advised against befriending 'writers' on Facebook. I am of the opinion that authors buy and read as many books as 'readers'. Already I have extended my 'to read' list from updates on FB. Books I would not normally have heard about. This is the internet age. Facebook is the place to show your product and meet like minded people. It follows that some of those people will be inspired to buy your books. If they meet with their approval word of mouth should spread interest. Makes sense.
Readers are often writers who haven't yet picked up a pen. I read avidly for many years, ( will not count how many) before I began to write. During those years I was busy with a paintbrush, creating portraits among other things.
So, although a huge following of readers should guarentee sales, I feel comfortable with a collection of authors as friends too.
At least I will never be short of something to read.