If rich people are this stupid then they deserve to be parted with their cash.
If you invest money so mindlessly that you don’t even check what you buy, then no legislation in the world will manage to protect you from your own mind
It’s not just rich people though. Most people (at least in the US) have their retirements and the like in things like 401ks, tied to some kind of index like the S&P 500. A company doing bullshit to manipulate the stock affects pretty much anyone who uses an index fund or ETF, which is pretty much everyone in the US.