Content Creators
These people generally do not bring fresh capital to the ecosystem. They create content, and get paid for it. Because many people in this group aren't affluent, and have life obligations and bills to pay, it is expected that they will be cashing out a part of their earnings.

Not yet, but give it some time. More users equals more content. More content equals more traffic. More traffic equals more options for making money, both for Steemit (advertising) and Steem (buying ads via Steem/SBD etc) :-)