There's no point in keeping your regrets so start moving on. There are still a lot of chances and opportunities that will come so let go of it. IMO, even if you sell your coins before another price increase, it's not totally a loss because you already made profits from the price you bought it. And everyone in this crypto market cannot make right predictions because of its volatility so it's just a normal thing for all of us.
Yes, you are right. After we get lost the money, we will have more opportunities to profit from the other coins.
As long as we know when we should sell the coin and how much profit we can get, I think we can prevent the loss, and no matter if our profit is not bigger than we expect, we still profit.
With the volatility of the crypto market, we should always calculate or analyze when we can enter the market and exit the market at the right time.
We do not have to make more profit if we think it will be difficult to do, especially if the market is hard to predict.
At the end of the day even if have a plan, selling early would make everyone upset. If we bought at 7k and sold at 21k, that would be 3x return, but when we see price hitting 40k we will still be upset about it no matter what. So, that is why selling early regrets will happen no matter what. What we can do about it is, basically never sell until we want to get out completely.
I understand that many people do not get in crypto with huge sums, so they can't get retirement amount of money that easily, if you invested 100 dollars when bitcoin was 1000 dollars (5 years ago) and sold today at around 40 thousand dollars, you would have 4 thousand dollars right now. That is a 5 year wait on 40x return, and even though that is a great return, you are still not retiring with 4000 dollars. But if you keep investing and keep waiting you may end up retiring with it, and do not sell until that moment. After that, you are retired with a lot of money, doesn't matter if you missed more money.
Selling too early will have a risk, which we should know.
But if the price can increase to $21k, and we already sold it for that price, the price will go down for a while.
Sometimes, the price can go down too deep, and we will have the chance to buy back Bitcoin at a lower price.
Bitcoin price itself will not always increase after the highest price, and the price will adjust to the lower price for a while or stay at that low price.
If you can buy back bitcoin at that time, your bitcoin amount will be bigger than before, so you will have more chances to sell it at another highest price.
Bitcoin investment will need patience, which will depend on how big the investors can wait for that.
If they can wait for a long time, they will get a big reward in the future, but bitcoin investment will benefit us because we can sell it whenever we want.