> "How does HFT provide social benefit to the world at large?"

It's explained multiple times in this very discussion. It's not our fault if you refuse to read them. But the most straightforward and obvious way is that it injects liquidity into the market, making it easier to sell when you need to liquidate. (It also reduces volatility overall, another good thing.)

> > the exchanges weren't established for the abstract sake of money, they were established to provide benefit to people.

Snort. The exchanges were established by wealthy people, for wealthy people, to engage in business with other wealthy people.

The NYSE was established in 1792. Is it your contention that anyone except the elites were buying and selling stocks in 1792? Let alone all the exchanges that pre-date the NYSE. The Amsterdam Stock Exchange was set up in the 1600s specifically to facilitate the buying and selling of Dutch East India Company shares. Was Farmer Aardhuis buying shares? Or aristocrats and royalty?