It is best to quit when you start to see signs that it is becoming an addiction. You can notice if gambling causes anxiety, stress, or discomfort. Generally, you tend to have excessive losses, so I recommend you escape from that situation and focus on other things to change your behavior. Generally, if you stop in time, you will avoid falling into addiction and be able to play again in a controlled manner.
The problem is that it's difficult to stop on time when you are making Profit, a lot of addicted gamblers I know got hooked because they made a lot of Profit when they started gambling. Addiction doesn't start in a day, it can take days, weeks and months. When it becomes a repetitive pattern it means that your brain have gotten used to it. When you feel anxiety when you are gambling because you are scared to lose then there's a problem