You buy a low-cost index fund (either S&P 500 or total market (Russell 3000, Wilshire 5000)), and depending on your risk tolerance, a bond fund as well.
You can have global diversification with one ETF or mutual fund:
* https://www.youngandthrifty.ca/picking-the-best-all-in-one-e...
You just delegated the choice of winners and losers in your economy to an elite cadre of individuals, completely disconnected from boots on the ground life problems.
Symptoms of your decision may include:
Tendency to centralize.
Preferrntial treatment of large incumbents for ease of implementing regulations.
Higher barriers to entry over time.
Decreased feedback loop with regards to reigning in egregious business malbehavior.
Index investing does nothing but perpetuate a small handful of winners, and divests the majority of people from their most important role of being capital allocators.
Part of it, is being bad at it at some point. That's how you get better and increase overall world awareness.
It's easy to say "they should have known" better because in absolutist terms it's correct. But you're focusing on the 'what' and not the 'why'.
For example: https://rollcall.com/2021/09/07/left-behind-by-financial-sys...
"Normal" investing is complicated, and stacked against regular people. Now we're asking people to understand blockchain and cryptography as well as investing. Yet it's sold as democratisation of investing. I mean, seriously.