These can be very different reasons. This will certainly differ from person to person. What is normal for one person may already be a sign that more than normal gambling is going on for another. If you enter an addiction phase, you should try to get out of it as quickly as possible. Write down the symptons.
It can easily be said than done to get out of it immediately. That's where the struggle starts for the addicted gamblers, they barely get out of it by doing it alone.
And most of the time, they cannot distinguish that they're already in the addiction phase because they are in the denial stage.