assuming the history of BTC from 2017 - 2018 will repeat this year, what you'll do with your BTC?
This depends upon the circumstances surrounding the reason on why the price of BTC dropped.
As for me personally, I would definitely purchase more BTC and HODL it for long-term. Any opportunity that makes its price lower in the market is also an opportunity for me to earn them. Another thing, I do think that people are taking for granted the technology of the blockchain and its application in the world. That is why I do think that prices of BTC will definitely skyrocket AGAIN in the upcoming future.
We are appreciating blockchain technology and its applications just because we are investors, we are users and we are compelled to trust the product we are tracking, the fact is that most people don't look down on bitcoin or blockchain technology, they just don't believe in the profits it can bring, I've never believed it either but I like to follow the trends of the crowd. And when bitcoin falls, at least I'll wait for a market trend to manifest, being hasty to invest and hold will make us lose more profit.