Throughout our lives our priorities change. At one point our priorities are centered around having fun and maybe later our priorities may be dedicated to a family. People's actions are a reflection of their priorities. If someone goes out to bars every night obviously having fun is a higher priority to them than the consequences such as spending a lot of money or not performing well at work. You'll find that when people's priorities shift, so does their behavior. When people cheat on their wives its because they have misplaced priorities where short term fun outweighs long term stability. In a similiar fashion when people spend beyond their means its obvious that short term gain is more important to them than long term financial health. Etc. But all that is required for someone to change their ways is for them to change their priorities.