Good question. Similar question: how sure are we that the whales in mobiles games or Casinos are not getting more benefit than we think?
The amounts spent are often quite substantial on the fan's side, while they are one among many viewed from the streamer's side. I don't think there's reciprocity.
There's not just the question whether the individual needs to be saved from themselves, there's also the question whether we let the predators roam free.
If someone believed they could cross the Atlantic ocean wearing nothing but shorts and flippers, you get to a difficult decision rather quickly. But if they're drunk and somebody is trying to guide them into a dark alley where you know three of their friends are waiting to rob the person, there's a good moral argument for a) saving that person from their fate and b) disposing of those four who are a net negative contribution to humanity.
It would take more than "documentaries", which AFAIK are always going for sensational, but false conclusions.