The moment when a habit can become a practice, it can also become a vice.
The difference is determined by an action.
After doing something for a period of time, a person can either come the fruitful action and continue on into another one, or else it can be complete with action and find resolution. At this point, a person is with option of continuing or changing action. If that action begins again without intention, it has become a vice. If a person engages a consecutive action intentionally and with regard to a deepening of the proficiency of the action, then it is not necessarily a vice. But it still can be.
The devil looses all ground and authority once the aspiring man recgonizes in a deep way the beauty of the moral life. It is the moment when he truly and deeply says “I want to be a maestro, playing my own life”