Honestly how quickly I forget about a loss depends on how invested I was in the outcome, which is probably the case for the majority of people. There's some losses in life I'll think about every now and then in a "life would have been quite different" way but they never dominate my thoughts so I think I'm doing quite alright.
If someone experiences a loss while gambling, they will quickly forget it, provided they don't mind the amount of money they have wagered. However, for a gambler who doesn't easily forget, it is usually because they are concerned about the money, and this really boils down to the importance of managing risk.
Personally, I don't worry too much about finances when I lose, because I usually have my own rules for limiting the amount I can afford to gamble, so I quickly forget about it. Furthermore, managing time is also important in gambling, so it won't become a mental burden when experiencing a loss. If someone experiences a loss during a time when it is not actually a leisure time, it is likely to weigh on their mind and make it difficult to forget the moment. So, the bottom line is that we, as gamblers or bettors, should be able to manage risk, time, and finances to get through the days safely and comfortably, especially if we gamble again.