BTC was $20k in 2017 December and $3.5k in 2019; following by gradual down movement. If you are strong enough to HODL, you are not likely to lose.
Not likely to lose all but when you have the peanut left, I guess that's what losing all the sum. I wasn't directly involved in trading back in 2018 but at that time, ATH for ETH was $1500. But after few months, we have seen ETH at below $100. It's for the 2nd market cap coin but in the case of shitcoin, people lost a lot. You can't lose it all literally but you have the chance to lose most of it because you know HODL is not that see as we can say.
If you look at history, of course this will repeat something new with a different price, where bitcoin has reached a new ATH I think the lowest price will definitely happen but I don't know how much for now I think the price is still high.
Investments this year will not lose all of it even if there is a decline, only the value of the asset decreases, so indeed you will not lose.
This will be different from knowing that before 2021, there must be an interesting story where it will be different. We can plant the word HODL. For the long term, starting a new one will definitely get good profits, no need to worry about high prices, we can judge bitcoin has mastered a lot in everything field.