The history of humanity is replete with examples of the slightly more technologically advanced group decimating their competition. The default position should be that uneven advantage is extremely dangerous to those disadvantaged. This idea that an intelligence significantly greater than our own is benign just doesn't pass the smell test.

From the tech perspective: higher order objectives are insidious. While we may assume a narrow misalignment in received vs intended objective of a higher order nature, this misalignment can result in very divergent first-order behavior. Misalignment in behavior is by its nature destructive of value. The question is how much destruction of value can we expect? The machine may intentionally act in destructive ways as it goes about carrying out its slightly misaligned higher order objective-guided behavior. Of course we will have first-order rules that constrain its behavior. But again, slight misalignment in first-order rule descriptions are avenues for exploitation. If we cannot be sure we have zero exploitable rules, we must assume a superintelligence will find such loopholes and exploit them to maximum effect.

Human history since we started using technology has been a lesson on the outcome of an intelligent entity aimed at realizing an objective. Loopholes are just resources to be exploited. The destruction of the environment and other humans is just the inevitable outcome of slight misalignment of an intelligent optimizer.

If this argument is right, the only thing standing between us and destruction is the AGI having reached its objective before it eats the world. That is, there will always be some value lost in any significant execution of an AGI agent due to misalignment. Can we prove that the ratio of value created to value lost due to misalignment is always above some suitable threshold? Until we do, x-risk should be the default assumption.