If you're new and bought in during December and now see huge losses... the worst thing you can do is sell now. Prices will increase in the long term. The current dip is just a correction to the wild excesses of last month. Don't panic!
If the prices you can see now are lower than the prices that you bought in at, then the best thing you can do is buy more. Why? This will lower your average entry price.
If you bought bitcoin at $16000 and see it now at $8000, the course of action is clear: buy the same amount at $8000, and your average entry point is no longer $16000, it's (16000+8000)/2=$12000.
Don't sell, buy!
i also think that nobody should sell anything, because up and downs are just normal and yes usually it's not a bad decision to buy low, if you have some money left. but somehow i can unterstand the people, which buy btc for such a high price like 18k per coin or more, that they prefer at the moment selling their coins instead of spending more money into the market, because some of them have put all their money inside allready :-)
i mean, as i can see on your rank, you are in cryptos since a while, so it's easy to say don't sell because you probably have not made any losses yet. but for people, whitch lost 50 per cent or more of their money over the last 2 weeks, it's a hard decision, especially to put more money inside the market :-)