There is only one way to prevent losing money and it is to hold when the value of Bitcoin is sliding down low. Buying Bitcoin is good anytime because when it comes to Bitcoin investment, it is advisable to be long term. And if you are planning to buy Bitcoin not because you want to invest in its growth but because you are going to use it as a currency, then the more reason that you buy it anytime. But if you are a Bitcoin investor, the better buying time is always when the price is cheaper but it is sometimes beyond our prediction so buying anytime is already good.