It stops working if enough other people do it.

True, any real phenomenon that is documented (e.g. that stocks tend to fall in December) disappears instantly.

No broker, investment strategist, fund manager, etc, is ever actually going to make smart decisions with your money because that dilutes the exclusivity of smart decision making. Which relies on scarcity.

I suspect this is the reason why they impose ESG on people's retirement funds. It's not hurting the fossil fuel industry or weapons makers, but it is depriving ordinary people of the profits of these endeavors.