Come on, you know that some people say that it is better to hold, some says that it is better to sell, and you ask the same people what you need to do??
Make your own decision. Look closer on the graph. Read some stories beginning from 2013. Analyze. And if you don't know what to do right now - buy! Buy and hold while learning.
You see the bottom? How far can it be lower? You think it can? You should all answers to these questions to know where to enter and where to sell(no).
So the last question is - what would you do now?