On one hand, I sincerely believe that when most people ask for attention it's because they need it for some reason.

However, without a doubt, there are those for whom attention seeking is manipulative and/pathological. I also agree with you that there are those, who for whatever reason, are locked into a very upsetting pattern.

You have to set clear boundaries with the former, with the latter I've found the best approach is to simply say "You know, it does hurts me somehwat to see you hurting like this. When you are ready to make a change, I will absolutely be here for you."