10%-20% is big, but since I've hold Bitcoin since 2019 and didn't sell during Covid pandemic, I would say that I'm not panic because I trust in Bitcoin.
If you have been in this market in 2019, you have have reacted panic in 2020 with March crash because of Covid-19 pandemic announcement from WHO. It's very challenging and stressful for newbies to don't panic sell at that moment.
You succeeded to hold your bitcoin because you joined this market earlier than 2019, that's true.
As long as you invest what you can afford to lose, I think you will not panic even though Bitcoin price falls really big.
If they started not with this mindset, they will not be ready for market volatility and will be most favorite targets of market makers. Less prepared means more easily to feel fearful and panic sell as expected by market makers when they release fud news.
Invest is for long term prospect, even though there would be many moments could make you in doubt, as long as you hold your coins, I'm sure you will not regret.
ROI from Bitcoin investment in long term is very good and it has been proven since 2009.
https://casebitcoin.com/