Let us assume you invested $190 when bitcoin price was at $19000. The price of bitcoin presently is $21000. The asset worth from $19000 to $21000 is $210. The profit gained is $20. The percentage gained is still approximately 9.5%.
To buy at low price and sell at high price is good, but holding longer for monoths or like 2 or more years may earn more profit after bear market, instead of swing trading after long time of having your asset in fiat or stable coin.
There is a saying that spot trading only takes pennies, while investing in the long term makes you richer. No wonder why buying and holding Bitcoin is the most ideal portion of the option. unless the OP does it on an altcoin it won't be too much of a problem. Unfortunately selling Bitcoin only takes for a little bit can't bring back the same situation in the future.