1. They fear that a superintelligent AI is coming, and that it will result in an apocalyptic event.
2. They fear that the capabilities of various AI technologies that exist today, or will likely exist in the near-future will result in people's lives worsening in different ways, such as jobs being lost.
3. They fear that misinformation will become very common and democracies around the world are at risk.
It's very difficult to quantify the risk of argument 1 occurring because we don't know whether the current state of the art will ever advance to superintelligence.
Argument 2 will probably happen to some extent, but what extent remains to be seen - you can already see that AI generated garbage is killing search, and with it a lot of the open internet as we knew it.
Argument 3 I find difficult to understand. Misinformation has existed for a long time, and AI is just one more way of making it (perhaps at scale). You've always been able to claim that your political opponent was a puppy murderer with no basis in reality - the way I see things, AI is just a way of laundering that kind of claim.