How do you know that it's the medication that allows him to "live a relatively normal life", and not the other factors?

If you want to trade anecdotes... My other friend's father fell out of a tree and broke his back when she was a child (iirc). Some time later they decided he was a "schizophrenic". He's been on antipsychotics ever since. His condition has spiraled downward over the subsequent years. Last I heard he was full-on crazy. If the doctors had provided supportive treatment instead of suppressive, his life trajectory would have been totally different.

My aunt's good friend had a "psychotic break" soon after her husband died unexpectedly. The friend was put on "anti-psychotics". She's now dying of liver failure, certainly as a consequence of her long-term drugging.

The ugly truth about so-called "antipsychotic medication" is that the class is palliative rather than curative, and actually causes the deterioration it supposedly treats.

Robert Whitaker makes the case that medications turns people's "episodes" into chronic conditions: https://www.madinamerica.com/2016/07/the-case-against-antips... and https://www.madinamerica.com/2018/03/a-tale-of-two-studies/ and https://www.madinamerica.com/2017/09/thou-shall-not-criticiz... , for example.