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 problem with humans is we always regret for what we missed despite knowing that there was a good chance that we might still not have entered it even if we had an idea about this thing. If I'll tell you today that this shitcoin could rise you'll still call me a stupid and might not agree with me but you'll surely regret it once you see it reaching new heights, fact is that your decision of not believing me was absolutely correct if factually this investment looked wrong to you, other than this you can't do anything more all you can do is trust your own fate.
Most likely, people make instant decision without doing some research at first, or making some moves so they will know if their decision is right or wrong. Then once their decision gone wrong, they will start regretting and continue to miss another opportunities again that could have change their lives. That is a wrong mindset. Yes, everyone is free to make some choices and regret it if things did not work out as planned, but staying in regrets and not moving forward will only make their situation worst, thus leaving them incapable to live their life at its fullest.
It's a part of journey and those who knows how to move forward will eventually find the something that will going to help them to forget about those mistakes that they are regretting, it's really tough focus again if you make a mistake or a decision that's something that can be a life changing but keeping it and continuing to regret and not doing any efforts to move forward will not change anything.
You are still alive and there are many opportunities in life even we really suffer from a big mistake, we should always look for a positive way to bounce back and recover to continue life.