Before you said people would be so arrogant as to not heed the warning, now you're saying the Zhat Vash woudn't be believed in the first place? I wish you'd make up your mind. I'd like to point out that I've gotten 4 different explanations from 2 different people as to why the Zhat Vash have never come forward. That's not a good sign. You're also completely ignoring the evidence the Zhat Vash have...
Completely ignoring the evidence the Zhat Vash have is
exactly what most people would do if they just were in the open preaching doom to anybody in the general vicinity. Do you read all those pamphlets printed in green Comic Sans that random people yelling on the sidewalks are distributing? They go straight into the first garbage bin you pass.
What I offered you were 2 different and separate scenarios, both hypothetical.
If the Zhat Vash came forward as a public lobby group and preached to the galaxy en masse, they'd just look like a doomsday cult and no one would bother looking at their evidence.
If they
instead came forward on a smaller scale, targeting people researching synthetic life and showing them the evidence, that's when the arrogant researchers doubling down on their hubris would come into the picture.
Not to mention, and yes, this is another different explanation, the episode itself showed that the vast majority of people who were directly shown the Admonition immediately went insane and most tried to kill themselves... that's not really conductive to spreading it throughout the galaxy. Jurati probably only survived with her psyche mostly intact because she saw it second-hand through a mind-meld. Until we're shown otherwise, I'd say there haven't been a lot of people with Vulcan heritage in the Zhat Vash who could telepathically transfer the same visions. Depending on how the recording works, one might have to watch it directly to see the evidence. And if the device projects the visions directly into your skull, their emotional impact is probably lost if you're just seeing an abridged transcript or video footage extracted via mind-probes. Without seeing the vision directly through the portal on the planet, your only context is most likely a random Romulan telling you "this is what happens if AI is allowed to exist", after which you're treated to some generic doomsday footage intercut with androids and fetuses. I'd guess in that case most people would only say "OK, robots and boom-boom, so what?", and walk away.