[merely-unlikely]

You're correct but I'd like to point at that professional investors don't understand all of that either. They spend their careers focused on little niches in which they can find an advantage. So it's less, what are the mysteries of the economic universe, and more, why does the West Texas Intermediate futures curve differ from the Brent curve and how can I profit from the spread?

That and the goal of many (most?) professional investors is not to beat the market. For some they just need to have higher returns than cost of funding and anything positive is accretive. Others sell fund investors on things like low market correlation. Or others have more specific goals like hedging future fuel prices for an airline.

Point being, individual investors have completely different goals from most professional investors and as you point out, "VTSAX and chill" is the way.

[tomatocracy]

For many professional investors (and certainly for a large class of asset management firms), the big incentive is to accumulate more AUM. Returns can be a strong marketing tool to do that, but they're not the only one.