alt Hacker NewsMarket makers are simply an artifact due to how shares are traded based on limitations that existed before computers. The aren’t some inherent aspect of having a stock market.
The money isn’t coming from thin air. If N people trade a a finite set of shares back and forth every day the only way to extract money from that set of people is for them to lose money.
Yeah, the stock market may be positive sum over the long-term, but it's certainly zero sum over the millisecond-term. Whether it's "retail" or "institutional" that is paying for HFT profits, it's all retail in the end.