Hey, @xplosive.
Good question.
According to the definition of investor I was going for, the answer to your question could be independent of daily active users, since the investor wouldn't be looking to 'use' the platform as such, but rather figure out the best way to passively earn their ROI. So not posting or curating.
However, to whatever degree each of us do it, we are investors, too, if we stake STEEM. I get that. I was just thinking of big money who can do anything with it and might choose STEEM, rather than most of us who come here to do some degree of blogging/social media, curating, commenting, etc.
Users obviously care about what goes on here, and that certainly effects the number of users, but churn is expected regardless. STEEM has been suffering in part by the fact that even if we had people coming to it in droves, they haven't been able to get accounts very quickly, even though HF20 was supposedly for ramping up onboarding. I'm really surprised that's never been a big issue. It kind of got lost because RCs kind of stole the show, but Velocity has never really happened.