Each of us has lost something somewhere at some point. Of course, there are some regrets, but remembering every loss is pretty stupid. Is it possible to replay it? Is it possible to fix it? No, it is not. Another important thing is that we must gain experience from our losses and mistakes and not repeat mistakes. The moment described by the OP, in which someone lost a huge amount of money, speaks of the person's passion. Having experienced the loss, he should have understood the reason for the loss and been more restrained in his emotions. If the lesson is not learned, there will be more such situations. The whole problem is in our worldview, understanding, and accepting experience as a lesson, nothing more.
Absolutely agree with you. A few years after the biggest loss I do not regret at all about what happened because I have learned a lesson that I remembered for life and which made me reconsider my views on gambling, the use of strategies and risk management. I am no longer chasing the winnings, but rather gambling for fun on strictly allotted for this money. I try not to exceed the established limits and do not try to win back losses as I realize that this can lead to even greater losses.