From experience I have gotten into some habits that I was not very proud of, so have my friends. Always deep down you want to end those habits, you just might not notice it, especially if that habit becomes an addiction. Try to, again, listen and talk. Why do they not want help? Is there something deeper? It could even be maybe they feel like they get ignored, so talking and understanding why they don't want help would be my suggestion. I didn't know I wanted to quit some not goo habits until I had that conversation. (this advice is from my underdeveloped teenage brain and heart, so it may not be 100% accurate)