The entire point of the Steem block-chain is that you get a fair payout for your efforts.
Since their aren't that many shops (yet) who accept Steem as a payment. People will have to convert their Steem to $$$. Because that's currently the only way to 'cashout' the reward.
Therefore, unless their is a bigger adaptation of Steem in the 'normal' economy. Steem will always be in a downwards trend.
With it's current jumps in price mainly because Steem is so undervalued compared to other cryptos.
Undervalued indeed. 2018 is looking promising for any Steem user.