Well, I believe you don't need a new year just to change your ways. You can always do it anytime. Maybe people are just inspired to change because of the feeling of something new for the new year or growth.
Exactly one don't need any reasons to have or create self control over their gambling habits but Instead it should be as a mark of remembrance or a sounding alarm whenever they want to gamble so as to limits and have greater control over gambling habit but starting something new in regards to having control over such habits begins with one's decisions and choice.