Lazy male friend/coworker - how can I help him?

I have a 21 year old male coworker with a few difficulties with mental illness. He recently attempted suicide and has a very bad case of ADHD which he takes medicine for. He also smokes weed in an attempt to help with his depression. We hang out after work and are friends (nothing romantic whatsoever, I'm married and he has a girlfriend etc), but his job is at more of a risk than he thinks.

He consistently comes in late to work and will have days of work when he hardly does anything for the entire 10-hr shift. He will come in on other days when he's motivated and will bust his ass getting a ton of work done and use that as an excuse to be a terrible coworker on other days.

We work nightshift in a warehouse, and all 4 of us on the night shift have largely independent roles so we don't have to depend on the other people doing their jobs at a similar pace (not sure how much sense that makes), and I feel like this is the reason why he thinks he can get away with this long-term.

Today, he was high all day at work and only did about 30 minutes of work during the entire 10-hr shift. He shrugs it off and brags about how much we can get away with on the night shift. Somehow he doesn't understand the severity despite being confornted by both our supervisor and manager about this.

I don't want him to end up being fired, but I'm not sure how to get through to him.
Lazy male friend/coworker - how can I help him?
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