I'm an active poster on Reddit and also follow on Twitter. My main motive is to discuss and engage with other people on certain topics. That's still the same here. I'm just fascinated by the blockchain backend and the possibility of being rewarded as a bonus.
I still post on Reddit - the community is much larger and the content is richer there. But I hope one day Steemit matures to the point I don't need to check out Reddit.