This is a right time to buy bitcoin but never a good time to sell. We may even borrow to buy so that when next the price goes up it will generate more profit. Also do not used all you have to buy at once because the price may still be going down day by day. It may work fine if you divide your money into different batch and buy bitcoin by batch weekly within this period of time.
We can't really say when it would be a good time to sell because people have different needs. With the price this high, it can even be argued that it's a good time to sell especially for those that jave kept their btcs since last year. As long as you feel good about it, its always a good time to sell.
But you are going to lose the rest of the profits that you could make, you should sell bitcoin unless you have no other choice but if you have it then it is a terrible idea to sell now.
I agree, there is no right time to buy or sell bitcoin, nobody knows if the price is going to decrease or increase more, what we can do is to do what our instinct tell to us, that way, we will not have any regrets on whatever may happen. Lucky us if we predicted the right thing, but how unlucky to us if it is the other way around. There is one thing that we should know, that if we have the opportunity to buy or sell some bitcoin, then do it.
The first part of the year was about altcoins and many began to question the strength of bitcoin but the second part of the year everything has been about bitcoin and its amazing recovery of its dominance in the market, lets see what the next year is about.