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.
In all phases in life, regretting is always insignificant and useless. That will not change anything but the fact that you are in a loss situation. However, you can’t change the past but you can always mold your future. So learn to let go and move forward by taking the risk now and investing into bitcoin. Your life will definitely be a lot different when you have bitcoin in your life compared to when you have nothing at all.
When we experience losses sometimes we regret and I think that is normal,
but if it happens excessively it's clear that it will only make it worse and a waste of time which is useless,
the future is much more important and we can change it for the better.