The rest of us believe that the human brain is pretty much just a meat computer that differs from lower life forms mostly quantitatively. If that's the case, then there really isn't much reason to believe we can't do exactly what nature did and just keep scaling shit up until it's smart.
The reason is because this has generally been how major discoveries have worked. Science and technology as a whole advances more rapidly when both R&D funding is higher across the board and funding profiles are less spiky and more even. Diminishing returns accumulate pretty quickly with intense focus.
I think there’s a good bit of hubris in assuming we even have the capacity to understand everything. Not to say we can’t achieve AGI, but we’re listening to a salesman tell us what the future holds.