You have to grow up with bitcoin. Most of the people that I know who had bitcoins in the early days made this mistake of chasing profits and selling everything at first high or first low. Then they kept observing how it moves and understood their mistakes. Some needed a few months to buy back, some a few years but they eventually came back and held for a long time, ignoring the short-term volatility.
Once you've been through a full bull-bear cycle you become immune to hype and panic.
I had the same experience in the market. I missed the 2017 bull run and that made me learn a lot of lessons. So, what I did was to take my time and create a proper plan. Invested back in the market when it reached its bottom price and I decided to hold it for as long as I can.
Although I never really was sure if the market would still be increasing in value again but I just made up my mind to invest the money and whether I’m going to lose it or not, I do not care. I was able to do this and hold for some years and luckily, I was able to benefit from the last bull run that took place. The thing is you should invest what you know that you wouldn’t bother about risking in the market. as long as you do that you wouldn't be much bothered at all and will be ready to hold.