I agree with what you just said. Regret is just a feeling of sadness and disappointment, but we can channel that pain into building our Bitcoin portfolio. Whatever has happened in the past has been done, we can't change it, but we can change what may happen in the future if we take a good approach now. It is in our hands whether we will regret it later in the future or not.
As for me, I have zero regrets. The only thing I felt sad about was that I didn't know about Bitcoin earlier. If I had known about it, trust me my portfolio would be reading millions of dollars through mining and earning because I had a keen interest in technology at that time. Good thing i can afford to buy with my DCA now. What's more important now is the accumulation stage i am in. Later in the future we will all be happy and that feeling of regret will never be known to us again.
I used to regret why I didn't start my bitcoin accumulation journey a long time ago, but we must not allow that to weigh us down in being consistent in accumulating bitcoin because we didn't know about bitcoin earlier and we can't undo the past, so we should move on and put the past behind. What our concern should be now is how we are going to accumulate the quantity of bitcoin we want to hold for the long term in a way that it will not stop us from sorting out our daily expenses. We are still early in accumulating bitcoin; if we are consistent enough in accumulating bitcoin, we will make up for the past we missed accumulating bitcoin.