"Indeed, as the attrition rate seems to be ~66%, it seems really important to understand why it is so high."
I have argued that the reason for this is the minnow-rewards are not great enough here: https://steemit.com/growth/@freewill/the-number-of-active-users-is-on-the-decline-let-s-talk-about-why-and-solutions
RE: Measuring Steemit Growth: What Every Investor, Developer And User Should Know