Yes, average humans are not beating the stock market. But the average human is a bit better than you give credit to.
The average human has never published a bestselling book. A person who has published a bestselling book is an above-average writer. And, therefore, an artificial intelligence capable of writing a bestselling book would be above an average human at the task of writing books. Therefore, somewhere beyond an AGI.
Attempting to redefine AGI to "being better than most humans at most tasks" is moving the goalposts towards artificial superintelligence.
I think LLMs are really impressive, but I suspect that we might have overpaid just a bit.