The thing with Bitcoin is that a lot of people are fond of complaining about one missed opportunity or the other, or how they wish they had bought at one time or the other, but imo, that's Bitcoin for you, and anytime is actually a good time to buy, and if you sell, then there is no need to regret it, rather look for another means of accumulating again, even if you start from the scratch.
Having said that, if it's altcoins in question, then if it pumps and you didn't buy when it was pretty low, then you can talk about missing an opportunity, cause it could prolly not rise/pump again and you didn't sell when you should have, but if you've done a good research into the history of the Bitcoin network and its price movements, then you'd understand that there is actually no situation of a missed opportunity, cause as long as you're not investing more than you can afford to lose, then you can chose to buy at anytime.
Perfect reasoning! I also think in this way, lost opportunities are now the past, now we need to think about how to grow with cryptocurrencies in a serious way, learning from the mistakes made! Crying is useless, react and try to do better!