I believe that buying bitcoin while its market price is down is the best thing to do when you are going to invest. As what i have learn, basic fundamentals of investment should always be applied that's when you buy low and sell high.
there are some difficulties that will be faced to implement it, for example to determine the lowest point. most people wait until the lowest point to buy, but they are too ambitious that they wait too long.
Predictions, lower points and higher points are hard to predict in crypto currencies. You can ask from anyone who is best at Technical analysis and he will tell you that even TA fails when it comes to prediction of price of bitcoins.