If that's the case it should drive most fund managers out of business since most of them don't beat the S&P over time.
https://www.cnbc.com/2017/02/27/active-fund-managers-rarely-...
And as more money gets funneled to index funds, the vanguards and fidelitys of the world could lower fees on their index funds which should put even more pressure on most fund managers which could create a vicious cycle. Maybe we'll be left with just index funds and a handful of rock star fund managers.