I hate coming across gangstalking people and groups online because it's just sad to see as an outsider and invokes strong feelings of wanting to be helpful but being unable to. Like you said, they reinforce each other in their bubbles so there's no way to get a message through that their problem isn't really what they think it is and they need professional help. And short of somehow magically only allowing helpful people to interact with those thinking they're being gangstalked (technical and logistical impossibility) it becomes another chance for trolls or other sufferers to just encourage more conspiratorial and paranoid thinking.