And some day, 10 or 12 years from now, there will be people that will say:
"If I had bought BTC in the early 2020's at $50,000, I would be a millionaire now."
If you don't want to be one of those people, then perhaps make the decision today that you weren't able to make in 2010.
Absolutely agree with you! Why blame yourself for selling bitcoins once, if you can invest now and earn several times more in time. Now is the perfect time for such an opportunity. Such a chance cannot be missed.