I think Stratis has a high level of volatility because many people who participated in ICO took out their profits, this does not mean it's not a good coin. Stratis, in my opinion, is one of the best cryptos at the moment. Beginning 2018 we should not see prices less than 10usd for Stratis or earlier. Perhaps another reason is that many people are cold storing Stratis, and whales are aware of this, so they take this opportunity to make massive trades and gain more Stratis coins.