Yes it was a bubble, and this is a correction in progress. A bubble just means that people bought for the sake of buying, without thinking about what they were buying. In a bubble, people buy in the expectation of getting rich quickly, and always believing that the price will go up with someone always willing to buy. December was a classic bubble Market.
We now have a correction taking place, the bubble has popped, and people are wondering why they were pumping money into the market. Then comes a stage of seeking someone to blame, with accusations of deception and fraud. Then people start sueing.
Nevertheless, blockchain and Cryptocurrencies are here to stay. The markets will settle, new legislation will be brought in, but the underlying promise and technology remains the same. People will now be more choosy in what they will invest in. In five or six years the process will repeat.