want to stop because stopping would be too painful, or they have not yet reached the point that they want to stop.

Part of the definition should include something along the lines of having such a desire to do something, that you are compelled to do things you otherwise would not do, to support the activity (stealing, lying, etc).

I also think knowing it is harmful, or at least that there will be unpleasant consequences, is part of the definition.

It's complicated.