First and foremost, your experience is not an isolated case. The history of Bitcoin is replete with regrets and missed or wasted opportunities.
That's what happens with an asset that has given such a return as Bitcoin. There were many people who knew about Bitcoin when it was worth very little, who had the opportunity to buy and didn't, or bought and for some reason or another sold, and now think about how much of a multi-millionaire they would have been if they hadn't done so.
I think even those who believed in the technology themselves didn't imagine that the price of 1 BTC would reach more than $60,000 someday, or else they wouldn't have sold. They would have accumulated more instead. Even Hal himself who thought that Bitcoin could reach as high as $10 million converted a lot of BTC during his lifetime. Perhaps they considered the possibility of Bitcoin becoming very expensive as remote, so much so that they didn't think twice of selling when Bitcoin was as cheap as a hundred dollars.
I think that better than regretting the past is to look to the future and not make the same mistake. The best day to buy Bitcoin is today. It still has a lot of profitability left to give.
I agree. There were lost opportunities in the past but there are still opportunities today. It would be a pity if we still let this opportunity pass.