We know how to do fusion. We know the physics behind it. We haven't yet figured out how to build profitable fusion plants, and we probably won't for a long time, if for no other reason than improvements in fission--modern fission plants are the best .
When it comes to AGI, we have no clue. It's a constantly moving target, because our conceptions of intelligence evolve. Most things that were once "AI" became "non-AI" solved problems after we got good at them using a couple key insights, e.g. that image processing could be sped up with CNNs due to the existence of a topology on the inputs. We still have no idea what makes us tick, and moreover there is not a strong economic incentive to replicate all of our intelligence... although, of course, automation will continue and that itself will be disruptive enough.
We're fairly certain it can be done given unbounded resources, we have some idea of the principles involved, but then there's a rather significant element of "draw the rest of the fucking owl" between where we are and where we imagine we could go.
He says AGI could happen in 20 years, not that he will single handedly manifest it into existence. That seems like a reasonable timeline given the field's current pace and may even be conservative.
If he's actual top talent as opposed to a poseur who's good at self-promotion, he should stay in academia for his own sake because he'll be crushed in the corporate world. Actual high IQ people get clobbered in corporate, while OKR-ing charlatans climb the ranks effortlessly... yes, even at FAANGs.
I'm not aware of anything he's accomplished but can see the delusion. ML people seem to think the output of their work is not mediocre. Yeah, you bred monkeys till something resembling shakespeare appeared to some reproducible consistency and it is better than something someone can code - but that's an incredibly low bar.
Acknowledge that were still very much in the stone age of AI and what were doing is large scale analytics at best.
Still.. do you think being a top talent in ML guarantees success for your own company, for example? I think there are a lot of valuable skills to have, being an expert in X is just one of them.