my advice:
stop thinking what you would have done in the past, the past is gone, think about the present, bitcoin price will always be high and low, so buy low and sell high. thinking that I had to buy it in the past is a big mistake, what if the price never went up? if bitcoin was a failure? how could anyone imagine that the price would reach $40,000? there's just no way to have a crystal ball to guess this
I think that's a pretty good advice.
Thinking about the past only helps you to not make the same mistakes again, and can help you to shape your future goals.
But after that's done, then there's no point in continuing thinking about the past, it will just waste your time, and make you lose other opportunities in the present.