A lot of it is marketing. Most of the "10s" that are constantly just posting selfies on Instagram/Facebook are doing it for work. They get paid for product placement, with the $$$ amounts based primarily on the number of followers / likes they get. I was reading about it recently, and it just seems so foreign to me. At the same time, I find the economics of it all just fascinating:
Why Snapchat’s Influencer Economy Runs on Hot Tubs, Selfies, and Whey Protein