The big surprise of the year 2018 is that the value of BTC is no longer rising and rising steadily as in 2017, in 2018 the price of BTC is decreasing and there is no sign of increasing like 2017. There are many reasons influencing value of BTC in 2018 as many virtual currency came into being and many investors bought BTC as the price of BTC fell
I do not think that the fact that the price of bitcoin is not growing in this year is any kind of surprise, if you take the time to look at how bitcoin has performed in every single year you will notice that after a great year the next year is not that good, and I do not find this really surprising, after all there is not an unlimited amount of money, investors need time to get more capital and until they do the market is not going to grow again.