It is very difficult to predict with certainty how low BTC will fall this time, but if you look at the current market developments it is very likely that BTC will drop below the $21k mark, because until now the crypto market is still experiencing a permanent and there is no sign of it yet the market will recover.
No one can but one can predict either correctly, almost exactly the same as the price or never got it right. What you said that it will drop to $21k mark is also a prediction. As I see that the current price is even lower than $21k as I post this one. I hope that it will not decrease more until it decrease to below $20k. Current price is at $20k+ and if it decrease then it os more likely to be below $20k which I think a good pricebyo start a plan to buy and hold long term.
It is already at a level where it makes sense to buy and hold long term. I am not saying that it will not go any lower, of course it could go lower but at the same time it is doing a good job being here as well. This is why it makes sense to start purchasing at the current price, it means that we are doing as well as it could be hoped for.
However, people are reacting as if they buy right now at 20k, and it goes to 16k, that would be the worst thing ever, it wouldn't be. When the price is 100k, the difference is negligible and you buying at 20k would mean that you would make 5x profit, and what else can you make 5x profit from? Not many things.
