The initial investment is the time and the 'shameless plug' factor are the curreny you pay into steemit. You have to 'shamelessly plug' your posts to everyone everywhere in hope of onboardng more upvotes. Also I'm seeing it feeds into a culture of people generating accounts to earn (rightfully so) but not necessarily putting in the efforts to put good content out there that is distincive and objectively adds value through newly curated content.