We regret about missing Bitcoin, then about XRP then about Ethereum then Doge then Shiba then Pepe (these are some top of my head and from what I've come across in my crypto term).
Point being there are always new opportunities and dwelling on regrets is futile.
The factor in common with all theae you've mentioned is risk, dont even try them if you can't take the risk at the highest level with altcoins investment, opportunities are coming everyday but we don't actually know which is better or not, we should also see it a great privilege that we are not involved as part of the experience of those who lost their investments at the cause with any of the then collapsed coins.
Thus is why we should know when to take advantage or when not to. But if you are thinking that it’s a great privilege or opportunity to give you life changing profits, then never be afraid to take risk. Losses are part of investing, but never end up regretting. After all, once you fail, that is not a total loss for you because it also gave you a lesson to ponder to be more cautious the next time you invest.