I think @dan's answer would be that traders bring liquidity and investment, leading to higher market cap and larger rewards for the social media side. It is a synergy.
And I would disagree that the rise in price and market cap has been funded by users. 2000+ BTC trading volume over the past few days on bittrex is not (primarily) steem users, it is traders and investors buying in, increasing the market cap, and making the entire system work better for everyone.
Anyway, perhaps @dan will have his own thoughts to share on this
Yes I agree it being a synergy, but it could wait IMO. As for the rise, i feel the demand was pumped up due to the interest generated with new sign-ups and believe they should have preference. Yes we will wait for @dan to explain!