Alphago is the equivalent a 1950s team coming up with a much better transistor that everyone expected to see in the next ten years in months
AGI is a 1950s team surprising absolutely everybody by secretly spending a couple of years and a couple of billion dollars and creating an iPhone.
By the time the iPhone was actually possible, everybody thought it was an impressive use of existing technologies rather than requiring multiple incredible advances and probably not even possible.
Even if you believe that AGI is as achievable as an iPhone, the idea that the wide spectrum of conceptual and practical AGI problems are likely to be solved by a single team working in secret seems more than a little unlikely.
A better analogy than an iPhone, is the Manhattan Project. A phenomenon is discovered and then published: uranium can be split by neutrons, which liberates a relatively huge amount of energy. Some scientists hypothesize that a chain-reaction that produces neutrons to sustain itself can be produced with uranium, but see no practical path to accomplish this phenomenon.
A couple of isolated groups of scientists then discover that certain nuclear reactions with uranium _do_ produce neutrons as a by-product, but in a way that is intractable to use for a chain reaction (too much mass required). Further research shows that the idea of a runaway chain-reaction becomes more plausible, and further discoveries supporting this are now considered dangerous and are no longer openly published.
Shortly thereafter, one group acquires unlimited funds and is able to discover exactly what is required to create an uncontrolled chain reaction. Over the next couple of years, it spends thousands of man-years to perform the vast engineering effort requried to actually accomplish this.
Almost everybody not directly involved with this research and development effort, are taken completely by surprise when the new phenomenon is publicly and dramatically demonstrated.
Is it really a better analogy?
The Manhattan Project had straightforward success criteria (either the chain reaction sustains or it doesn't), was undertaken at enormous speed not least because scientists working on the project were convinced that even with limited information already in the public domain there was an imminent threat of the Germans building one first, and especially in those circumstances was unlikely to produce plausible useful byproducts before the success criteria was met. More of the budget was spent obtaining the fissile material the theory required through industrial-scale application of experimentally-known techniques than trying to figure out just what it was that made things go boom. The bomb test worked first time.
By contrast, AGI has been desired and actively and openly worked towards for decades and we haven't even decided what it is yet. And it's hard to imagine the intermediate non-threatening intelligences and their byproducts wouldn't be so impressive an advance that those working on them wouldn't be willing to share them. Without wishing to trivialise the immense amount of intellectual effort and industrial production that went into the Manhattan Project, sentience is a more complex goal than a chemical reaction. Or indeed an iPhone.
AGI is a 1950s team surprising absolutely everybody by secretly spending a couple of years and a couple of billion dollars and creating an iPhone.
By the time the iPhone was actually possible, everybody thought it was an impressive use of existing technologies rather than requiring multiple incredible advances and probably not even possible.
Even if you believe that AGI is as achievable as an iPhone, the idea that the wide spectrum of conceptual and practical AGI problems are likely to be solved by a single team working in secret seems more than a little unlikely.