The short answer to your question is because it’s an addction. Once we have crossed the line into compulsive gambling there is no going back to “normal” gambling no matter how long a break from it we have.
I’m seing some god news here though – you already know you can “give up gambling for months.” This time though use that time to get some barriers in place, to get into the routine of using support, whetehr that is here or anywhre else. Then keep up that routine to help maintian recovery. This time you can give up gambling for months and then still be using support, still have barriers in place and be a lot less likely to return to it.
Keep posting.