If they did not keep track of their records, it is possible that they would simply set aside a limited amount of money for gambling in order to keep their own losses under control. It's depressing to know how much money you've lost over the course of your gambling career, but it could be a sign that you need to stop gambling or put some restrictions on how much you gamble.
And that is one of the massive advantages of record keeping, if you look at the amount of money you have spent gambling over the years and you cringe about it and you think you have lost a lot of money, then that is a clear sign that you should slow down for a bit or even stop gambling for some time, as in my particular case I do know that number, or at least my best estimation of that number, and I do not have any problem with the money I have lost over the years.