> This depends on which stock index you're looking at. If it's the S&P 500, it's a cap-weighted index. 50% - not a typo - is made up of 5 companies: Microsoft, Apple, Amazon, Alphabet and Facebook.

I think you need to check your math on that. It's way off. I haven't read the rest of your post but if anything else in there is based on this error, it's also wrong.

https://www.ssga.com/us/en/individual/etfs/funds/spdr-sp-500...