Sad truth number 2 is: We can't control our fellow enablers, either
Yes, his parents will want to 'save him', to keep him from feeling any pain or experiencing any consequences. The truth is, they are keeping him from maturing into a responsible, self-sufficient adult. Only they don't see it that way, and there is nothing you can do to change that, either.
Denial is something that we use, too, to keep us from acknowledging the truth about how bad the situation is when living with an active alcoholic or addict. Some of us have been with an alcoholic partner for years.
I wish I could tell you that there is some magic phrase or way of explaining it to him or to them that would break through the denial--but there isn't. What you can control is your own environment, the sort of behavior that is acceptable for you to be around. I really like the hula-hoop analogy. Imagine yourself standing inside a hula-hoop that is lying on the ground: What's inside the hula-hoop, you control. What's outside the hula-hoop you can't control. It doesn't belong to you.
Frustrating, right? But true....