Even supposing that HFT adds no value to society (which is an incorrect assumption as many commenters have already pointed out), this particular argument is pretty inane in my opinion.
There are perhaps 4-8 significant players in the HFT space, all employing anywhere between a few hundred to a thousand people. Probably less than 5000 people total, and if you only include programmers and quants, maybe less than 2000. Google alone has 30000 programmers. How many of them are optimizing ads for eyeballs vs “benefiting the country/society/humanity”? What about the thousands of programmers making video games mechanics more addictive for children? I think it’s silly to focus on one tiny industry, and demand that those people should be working on things for the good of humanity, when the fact is the vast majority of humans just work for their own livelihood. I mean, what do you think 95% of the people in SV are doing? Not every company is trying to cure cancer or explore space...
HFT is such a small, niche, industry, and also extremely productive per employee relative to most other industries. (the primary reason for comp being so higher). It replaced the thousands of manual traders that used to be responsible for arbitrage and market making with automated robots, dramatically increasing market efficiencies while reducing the amount of human capital required to provide those services. I find all the virterol towards hft from SV very puzzling, as it seems to exemplify all the things that SV espouses!