I'm not saying I think either scenario is inevitable or likely or even worth considering, but it's a paperclip maximizer argument. (Most of these steps are massive leaps of logic that I personally am not willing to take on face value, I'm just presenting what I believe the argument to be.)

1. We build a superintelligence.

2. We encounter an inner alignment problem: The super intelligence was not only trained by an optimizer, but is itself an optimizer. Optimizers are pretty general problem solvers and our goal is to create a general problem solver, so this is more likely than it might seem at first blush.

3. Optimizers tend to take free variables to extremes.

4. The superintelligence "breaks containment" and is able to improve itself, mine and refine it's own raw materials, manufacture it's own hardware, produce it's own energy, generally becomes an economy unto itself.

5. The entire biosphere becomes a free variable (us included). We are no longer functionally necessary for the superintelligence to exist and so it can accomplish it's goals independent of what happens to us.

6. The welfare of the biosphere is taken to an extreme value - in any possible direction, and we can't know which one ahead of time. Eg, it might wipe out all life on earth, not out of malice, but out of disregard. It just wants to put a data center where you are living. Or it might make Earth a paradise for the same reason we like to spoil our pets. Who knows.

Personally I have a suspicion satisfiers are more general than optimizers because this property of taking free variables to extremes works great for solving specific goals one time but is counterproductive over the long term and in the face of shifting goals and a shifting environment, but I'm a layman.