Nobody can predict the fluctuation of the price, but I am very surprised that the price has moved from 800USD to 900USD in a little span time. Like the article mention is very risky to trade at this time because the price can also move down.
The best strategy for myself was always keep and hold my bitcoin.
That is a good strategy. However you will never make money if you are not risking, and the more you risk the more you can earn. I'm not encouraging anyone to risk a lot to have big profits though. Risk only the amount you can afford to lose. But in times like this you can definitely earn more with trading than in times of stability. You should just do it carefully and responsibly.
They predict in the article that the price might drop to $820-$830 for a short period of time. That would be a great time to buy IMO.
