It can happen mostly when you newly started gambling, after losing so much money, you can just get bored and frustrated at the same time and you might just decide to do what ever your mind tells you to do without giving any second thought to what you are doing. At that moment it doesn't matter to you whether you know what you are doing of not, you have submit your self to 100% luck and not any form of common sense application. It happen to me when I first started gambling some years back.
losing at gambling is a normal thing, especially when someone is just starting out at gambling, it seems that most of the gamblers make mistakes that result in their losses. the most important thing is how we respond to this and not think too much about the loss, let alone gambling continuously to be able to chase the loss, that is quite careless and it could lead to addiction. it would be better for gamblers to respond more wisely and not gamble excessively when they lose. taking a break can be done so that gamblers can reduce the potential for even worse losses.
Starters supposed to win more. It is either because of beginners luck or it was only the casino making them believe that making money at them is so easy.
You already said that losing is a normal thing, so it is not about making a mistake and I believe there is no such thing as mistakes but all actions are intended and the money spend is not wasted but the person do also earn a benefit including a lesson if they regrated their actions. No it's not the loss that they are thinking but it was the win and if only they will think about losses, this is the time that they will stop and there is no guarantees for them to return in the gambling arena again.