Another thing the HN orthodoxy rejects is that professional investing and trading can make money above monkey-dart levels, despite the abundance of evidence that it does.
I used to work in sell side equity research before leaving to do software development, because at least from my vantage point, no one was that great at predicting the market.
Example PDF showing this: https://us.spindices.com/documents/spiva/spiva-us-year-end-2...