It seems that there will be a similar rebound at the end of each year. This is also true in the stock market. There will always be a wave of "Christmas market" on Christmas Eve every year. At the end of the year, there will always be some preparation for next year, so the market may rise.

   Bitcoin seem always rally in December , I don't think so the prices is affected through the demand and the supply. In December it is because of the holiday season so many are spending that's why seem the prices is going up..

December Holidays is synonymous with a lot of giving gifts to people thus a lot of exchanging of bitcoin to fiat is usually the order of the day invariably affects the price of btc which is more or less resulted to a drop in the price  until the holiday is over before any noticeable bullish runs currently the price is showing some flashes of bullish run

There is no exact correlation whatsoever between Bitcoin price and any holiday. It's just a coincidence but there are year as far as I can remember that Bitcoin didn't rally at the end of the year. Last year alone, there are speculations that after Chinese New Year, Bitcoin price will go up because Chinese will go back to the market, but it didn't happened. I can only speculate that whales are just manipulating prices and giving false hope that a break out run is really happening every year end. So if you're a noob investors, you might get caught in this trap, so just be careful.

It looked like a rally with prices rising for around a week but it was not sustained so it is therefore categorised as a small correction following a massive dump. The rally is likely to begin after the bakkt next month

This is obviously not true because this December shows totaly different situation. That small price rise that we had after cointinuous price fall can't be called rally. It was just slight positive correction that didn't last for long.
After all this time that I'm dealing with Bitcoin and that is for five years by now I can't say that there is any prooven connection between Bitcoin price and some periods or months in year, there are always different factors that influence the price.

Price can change any time. We can't mark any reason surely. We can't say that only in December, price goes down. May be in December in next year, price will hit the record price. We can speculate but we can't mark anything surely.

A lot of them say in Christmas holidays most them prefer to buy cryptocurrency as they don't want to spend unnecessary so the value of BTC goes up, but it doesn't work upon that. Only if the demand and supply is low the value may go up.

i dont know but i think it is like the event, from last year and 2 years ago we can see that the price of bitcoin is always increasing at the end of the year at december, so all people will buy more bitcoina t december

At the moment I am very worried about the price of Bitcoin, very worried if Bitcoin next year will experience a very drastic price decline, because that can happen, because no one can predict the price for now. Hopefully by the beginning of 2019 the price will be green and so on.