I don't generally disagree with what you said, and I'm largely just taking an opportunity to go on a rant.
I have to ask -- is the stock market system really "the least worst option we have"? From an interpretation of "have" being "that is implemented and running", sure, but that's just tautological. It seems easy to conjure up systems where speculation isn't rewarded like this[1]. It just tends to mean no more instant-million or billionaires made out of people who run profitable businesses.
Recall that investment was initially about sharing profit in exchange for the funds to grow a business. Part-ownership. But we made those ownable pieces sellable, and people became able to make more money by selling little pieces of companies than by holding onto them and realizing profit; the system has evolved to grease those wheels.
If we were collectively prepared to be a little less greedy and insane, the majority of this risk would go away. We don't have to trade speculatively on future expectations of the value of the ability to sell the right to take part in a company's profits. The world could exist without stock markets, and it just means that a lot of smart people might be working on real problems instead of shuffling money. That world would look very similar to ours, except that absurd fortunes may not be come by so easily.
[1] Quick ideas: Stock ownership is non-transferable, or Stock-ownership is limited-term, or Stock ownership is limited yield, or Stock ownership is transferable after a fixed period. These could favour the rich and those with knowledge of the system, so perhaps provisions about sales would be required, "X% made available for individual buyers of less than Y value" or something. Pretty much any system which removes the notion of a real time market based entirely around selling a company's stock seems to fix the problem. It appears to me that there are a myriad less worse systems, judged by the metric of how many people are injured by the system, and how badly.