In documentary we don't typically pay people anything to tell us their life stories.
Interview them for free, you're making money without compensating them. Interview them and give them part, you're exploiting them by underpaying them. Interview them and give them all profits, you're enabling their addiction. Give away the non-ad revenue, you're just abusing a tax writeoff. Don't give it away, you're enriching yourself.
Your economic ideology seems quite fluid, and seems to lack internal consistency.
There’s three options for remuneration.
1. Pay nothing
2. Pay them for their time
3. Give them a large cut
If the contention is that they may be junkies then 3 is probably not a great idea, better to give the money to charity.
If the contention is that it’s exploitation then surely 2 is less exploitative than 1.
In the end, giving people a voice who don’t have one currently is the complete opposite of exploitation.