How true that is depends on how you define "better". But we've been making lots of tools over thousands of years that can perform tasks better than people. You need more than that to declare a thing "intelligent" in the sense the average person thinks of it.
> To place your bet that we will never reach AGI is bone-headed.
Never is a very long time, but I think it's a solid bet that it won't happen within the next few decades, at least.
> Why is this the default assumption until proven otherwise?
In the absence of solid evidence for the existence of a thing, assuming its nonexistence is the logical position.
> We need to prepare society for AGI (or prevent its creation) well before it is realized.
We agree on this. But that's not what's happening. What's happening is some people are scaring the hell out of other over an imminent that there is no evidence exists.
We have lots of time to consider these things carefully and to react with calm prudence.
> So the course of action that maximizes utility is to assume we're close and prepare for it.
Not in the way it's happening. The way its happening will, in my opinion, actually increase the harm that AI is threatening to cause, and will distract from the actual risks that AI as it exists right now poses.