There are marginal benefits outside of HFT. Mostly, the spread in markets (difference between sell price and buy price) shrinks because of HFT. Hence people wh

There are marginal benefits outside of HFT. Mostly, the spread in markets (difference between sell price and buy price) shrinks because of HFT. Hence people who want to make financial transactions have less friction. In order to interpret this as a global positive, you need to see a more efficient financial system as better. The story there is usually that a more efficient allocation of capital allows for the most growth, pulling more of the world out of poverty. (I fully think HFT is good for financial world, less certain on the financial world being better for the wider world)