What have you lost the most money on and still regret it to this day?
Something else... Really far from gambling, although every reason why I lost so much was all my fault, but mistakes are to be made... What blends the process is the acknowledgement and change.
So I looked at the comments and most people said that they regret losing their own money on bets, and one of them even lost 30 thousand.
Are you in doubt? 30 grand to some is like a change from purchasing McDonald's chicken and fries.. BTW, I don't even know what currency you were referring to.
I haven't lost so much that it became part of my story/ my deepest regrets. When the going is good, I ride with the tide. When it starts getting rough and tough, I just look out for it and catch up in time. Every single bet is planned and focused on a goal - if I win, good, but if I don't, so be it.