According to their whitepaper,
Steem Dollars were designed as an attempt to bring stability to the world of cryptocurrency and to the individuals who use the Steem network.
Unlike its purpose, however, I can see that it has severely fluctuated in recent months especially between last Dec and this Jan like most other alternative coins from CoinMarketCap.
I guess it's cause it has been able to be traded in some exchanges like UPbit for some reason outside of Steem ecosystem so it has lost control of Steam Dollar even with the help or responsibility of their witness (but I've never traded crypto currencies before so am not sure whether it's possible to trade Steam Dollar on that exchange).
Do you have any other opinion?