...can't quit without side-effects.
Most addicts can stop using immediately with the side-effect that becoming less productive/energetic.
For THC, it is relatively easy to mitigate most side effects by adjusting the dose.
Modulation is not the key, but helps a lot
To me, I feel as though that behavioral addiction is completely disregarded by the medical community. If someone is lighting up every night / having a drink and want to stop, they need an alternative way of closing out the day. Otherwise of course it'll be difficult.
1. Imagine you're going to Walmart. You see a friend. "You say hi and raise your hand to draw attention" However, they walk right past you without even acknowledging your presence.
What is your first thought? Maybe "Jerk!", "he's busy?".
You don't have control over that first thought, but you do have control over that second thought and your actions thereafter. Addiction messes with your first thoughts and attention. Next scenario
2. A wife and a husband are driving down the road. The wife notices Kohl's is having a 50% off and the husband notices that Andy's liquor store has two six pack for the price of one.
In this case, due to addiction, the husband noticed that Andy's liquor store and that's a craving. His awareness was drawn to that sign with a subconscious cue influenced by addiction.
Therefore, someone who wishes to maintain sobriety has to be very self-aware of their thoughts and actions. They have to guard themselves from triggers, situations, people and then manage those other aspects they can't control.
It isn't helpful for people to view themselves as simply a character flaw when going through addiction because their brain is scarred. It doesn't mean they can't make poor choices and not choose to maintain to pursue sobriety. Their behavior matters and their disease matters.
Obviously the progression doesn't happen as fast for some. However, the key being they can't quit in moderation or in excess. Some can abstain for 3 months, some for six, thinking they don't have a problem but then find themselves using even a little. There's a self-rationalization as well as self-centeredness that's part of the disease process of addiction. I would say it's not only a disease process but it is a huge factor. Cross addiction substituting one substance for another is also part of that self-rationalization.