This is interesting. I've been using Streemian to auto-vote on a few favorites, just because I know I may go a day or two offline before I see their posts. But it's not for any kind of ROI. It's because I want them to know they have my (very modest) support.
Now if I'd poured a huge investment into Steem, rather than earning every coin by posting and interacting, maybe I'd feel differently. But I doubt it. Mostly I want to reward the creators I enjoy, because I want to come back to a place that's full of great stuff to read.