That sounds like a horrible experience, and I hope you friend is being treated better now.

To be charitable and more specific, If you are stable enough there's nothing technically stopping you from not taking prescribed medication and self medicating - as long as you remain stable enough to not warrant involuntary treatment. The obvious risk is if your prescribed medication (or a combination of prescribed and self prescribed medication) is making an impact, you could get worse.

From this comment it sounds like there's a lot you're leaving out of this story, but I'd like like be caucious of making generalising statements from specific personally related scenarios.