The worst mistake I did was not to sell/use my bitcoin when the price was $1200. But the price will be higher in the future.
Not a big mistake in my opinion.
At that time mayn others might have thought as well that it would continue rising after a short correction.
And as you said, we will see these highs again.And we will move to new ATH.If you are patient you will get another chance to sell for a nice profit.