Basically the argument is if anyone, anywhere creates an AI that has the same basic drives as a human (preserve yourself, replicate, preserve things that look like you) it'll start competing with us for resources. AIs have demonstrated the ability to crush humans at every competitive game we can play with them, so they'll crush us at that game too. It looks a bit far fetched in 2023 but it is actually pretty easy to see it happening. Hardware progresses exponentially for a few more years. Some war-torn state gets desperate, starts deploying military AIs to try and get an edge, loses control, yada yada. Or economic pressure starts engineering humans out of the loop in one too many places and evolutionary pressures happen by accident to develop an intelligent autonomous agent that wants to replicate.
Humans struggled with a cold virus recently and couldn't stamp it out. Something that can outdo us research-wise would not be something we can handle. Whether humanity has control of corporations is an open question given the number of people who get killed if it is profitable to do so. We've been luck that corporations need people to act as a brain. AIs don't need that.