We can't conclude that rewards aren't the problem, but we can at least conclude that absolute value of rewards does not seem to be the problem. ie. Simply increasing author rewards or having a higher price will not fix our user retention problem.
There is something (or some set of things) which is causing us to basically lose 30% of authors every month, relying on new authors or returning authors to replenish numbers. What that/those problems are, are not clearly identified here.
Unfortunately I believe a big percentage to that may be from some abusers that seem to focus on creating fake intro posts, mostly either stolen from steem or other places of people holding up a sign that they lazily edit. These abusers all have one thing in common, they create one post and do nothing else after that so it may be a big part of your stats of leavers.
Good point. It might not be straightforward, but it may be possible to do some sampling and estimate what proportion of accounts are just catfish style accounts that are not desirable in the first place.
Don't draw any conclusions yet. I think a lot of it is RC related. I don't know if you play Splinterlands or not but I think new accounts get like 2-5 HP powered up or something. They try posting or commenting a few times and then find out they can't actually play any more because of insufficient RC.