I don't know how to make sense of this level of investment. I feel that I lack the proper conceptual framework to make sense of the purchasing power of half a trillion USD in this context.
The thing about investments, specifically in the world of tech startups and VC money, is that speculation is not something you merely capitalize on as an investor, it's also something you capitalize on as a business. Investors desperately want to speculate (gamble) on AI to scratch that itch, to the tune of $500 billion, apparently.
So this says less about, 'Are we close to AGI?' or, 'Is it worth it?' and more about, 'Are people really willing to gamble this much?'. Collectively, yes, they are.