Regarding your first assertion; haven’t we already reached that level of power?
Yes, nukes might be called the first existential threat technology. My point is that an accelerating knowledge explosion means more threats of that scale will emerge. Success will depend on successfully managing every one of them, every day, forever.
Nuclear power is strong enough to wipe us out, what difference does it make if it takes 1 nuke or 20.
It would seem having 20 technologies of that scale is indeed a different situation than having just one.
The level of power however stands in no relation to it’s manageability. Only because a product is more powerful does not mean that it is therefore less manageable.
The level of power means there is less room for error. With more modest technology, we can screw up, and then fix it. With "existential threat technology" that option may not be available.
Therefore I do not see the proclaimed inevitability of an unmanageable power.
You are in good company! Everybody argues for the "more is better" status quo because it is a very old and happy story we don't wish to part with. I believe the happy story might possibly be preserved, but not by pushing forward blindly with the status quo. My argument is that we've reached a point where our "more is better" relationship with knowledge needs a review and update. We will either learn this through reasoning, or through pain, more likely the later.
-- Updated February 9th, 2016, 7:10 pm to add the following --
If you think that you can stop people asking questions and wanting to know answers, well, good luck with that one.
I'm inviting readers to ask deep questions about our relationship with knowledge. It's my critics who wish to not conduct that investigation.
I am with Greta; we may be blithering into the unknown but that is all we can do and we have to try to make the most of it,
But that's not all we can do. We're already doing what I'm suggesting right here in this thread, having a conversation about our relationship with knowledge. There's nothing stopping us from having a long, deep, serious investigation in to that relationship. There's nothing stopping us from questioning dogmas that may have been an excellent idea for a long time, until we entered a revolutionary era characterized by a knowledge explosion.
On another forum some scientists said essentially what you said, there's nothing we can do, there's no point in even discussing this etc. And then they proposed spreading out across the galaxy as the solution. They lacked the confidence in their ability to have a conversation, but did have confidence we can migrate across the galaxy. These are not reasoned responses, but emotional ones. Apologies, but such emotions are essentially nothing more grand than intellectual laziness.
If the things we want to hear could take us where we want to go, we'd already be there.