Your dad didn't fail because he's weak. He failed because nothing addressed what he actually needed.
Stubborn people don't do well with patches or gums because they ask him to change everything about his routine while getting nothing in return but more addiction.
That's not how humans work.
He's done that motion 20+ times a day for years. Decades, maybe. It's automatic. It's comfort. It's ritual. They need a replacement. Something to do with their hands. A ritual that feels similar enough that their brain doesn't revolt.