You have to be good at analyzing so you know the risks and which trade is worth it. If you are not good at that you will be bankrupt quickly.
Of course it is unpredictable because the price of cryptocurrency is not just based on the market but also on the sentiments or psychology of the users. Even if the graph says something, it can still go the other way. All we can do is speculate and hope our speculations are right.
Its a normal thing on trading that we suffer such losses because we cant guarantee our selves to buy bitcoin in an exact time since price is too volatile. if you loss in $650 then how much more on those people who bought when bitcoins price reaches $1200 ways back before? Then for sure they would wait until the price would reach that amount or even higher.
If the bitcoin price drops below $550 again, that would be a good time to buy. If it rises to $700 in the next month, it is good price to sell.