> It seems to me that the field contributes nothing to society, and has only negative externalities like raising barriers of entry to markets and using insane amount of resources.

I thought the same way for a long time.

HFT helps make markets more liquid and (somewhat) may aid price discovery.

Now, assuming you buy that, the standard response is “sure, but how does pouring all these resources into shaving picoseconds off of a transaction help the world?” Fair point.

In my mind, the markets are really just a giant computer running a resource optimization problem whose inputs change constantly. Improving the latency of getting a result back can open up completely new applications.

This is a bit hazy, but think of what is possible with todays computers versus those of fifty years ago. Both can perform the same calculations, one is just faster, yet just making calculations faster has changed the world.

HFT means speeding up the computations for the allocations of resources for the entire world. This is a really important set of calculations- it affects, indirectly, almost every human on the planet. Making this faster by just a tiny fraction can make it more efficient and when that efficiency is multiplied by the trillions of dollars involved, that can mean huge savings for humanity as a whole.

Or, you know, the benefits could all be spent on hookers and cocaine, your choice.