They might as well invest in cold fusion, warm superconductivity, curing cancer or whatever sci-fi concept you have.
If you don't see "AGI is possible", you aren't looking.
"The ability to speak does not make you intelligent." - Qui Gon Jinn
Modern LLMs show empirically that the "difference" is fuzzy at best. You can try to draw a distinction. You can try to draw the lines in the sand and define "true intelligence" in a way that would include humans but exclude "false intelligence" of Mythos 5. An exercise in vanity, in my eyes.
Or you can go with "any sufficiently advanced language generation is indistinguishable from intelligence" and drop the matter. My advice is to do exactly that.
The act of distinguishing between human intelligence and LLMs is what allows us to figure out how to make it better. There are still some deep limitations, and to ignore them is a mistake. That doesn't take away from how crazy good they are.
But I never forget that it's a simulation of intelligence. I use it for the things it's trained on (generating code) and I don't expect the model to be good at writing poetry, or fiction. Nor do I expect it to have any actual understanding of the things it is actually trained on. Modern models are pretty good at simulating understanding, but even so they will still produce things that a human being would immediately know is wrong, e.g. image-generation models producing hands with the wrong number of fingers, or a person with three arms, or whatever. Those happen less and less often as models have been better trained (and I bet that verification steps are happening behind the scenes to catch and discard some of the classic mistakes), but they still happen.
It's the dancing bear, except this bear is actually managing some really spectacular dance moves. Some of the time. Other times it falls flat on its face. But it's really, really impressive that the bear is actually managing to dance so well.
So all they have to do is wait a bit and build a frontier model of their own.
In telecomms, the late mover has the advantage of not having legacy networks to maintain, and having better technologies available at rollout time. What is the "late mover advantage" in AI? Being able to distill from every bleeding edge frontier lab? That gets you near parity at best.
So they don't spend 20 trillion dollars to achieve AGI, and in the end they still end up at parity for a tiny fraction of the cost.
How can you claim that this isn't a win?
You can't distill or catch up if you can't access the models. You'll basically have a situation where nation-states will need to try and steal the models Oceans 11 style.
In all seriousness though it is pretty interesting to consider if it really happened, a sovereign wealth fund pivots to the crazy high risk strategy, writes a blank check and tries to actually win. If it works does that country just become the rulers of the world?