It is illegal on some stock exchanges. You are free to only buy your shares there. Also you are free to buy stocks on exchanges that do allow it but don't have two classes. No one is forcing anyone to buy Meta

Sorta. Meta is a component of the sp500. It’s pretty difficult to avoid buying that.

Just go beat the market.

Buy shares of the other 499?

It’s also weighted by market cap which makes this a pain to manage.

Actually, you don't even need to go that far, because once you get sufficient coverage of the S&P you're incredibly well correlated.