because addiction in gambling is just about mind thinking not like in other vices like drugs,smoke,and liquor that it is our internal that seek for this , but in gambling mind control is what we only need .
I'm not sure if 21 days are enough if you have an addiction though. Some reports suggest that any addiction affects the brain to a similar degree, although there is a clear difference between gambling addicts and other forms of addiction[1]. Not to mention any gambling-like mechanism like gacha game can stimulate our brain just like when we gamble with money in a casino. That being said, we need some time to cool off from any addictive behavior and spend more time on physical activity or social activity to enhance our prefrontal cortex connection so we won't get impulsive to seek dopamine as soon as possible[2]. CMIIW.
[1]
https://www.apa.org/monitor/2023/07/how-gambling-affects-the-brain[2]
https://www.gatewayfoundation.org/addiction-blog/how-gambling-affects-brain/