I&#x27;m not sure I understand these jobs in an economic sense and I still am not sure of the value they provide to society. Does solving liquidity or arbitrage issues a few microseconds, or even seconds, faster than someone else improve productivity? Or when it doesn&#x27;t depend on speed but on seeing some tiny market inefficiency, how much does that help the world? (And I&#x27;m sure I&#x27;m overlooking other economic activities in these firms - what are they?)<p>There&#x27;s the economic question of why the market rewards them so well (not that, in the real world, the reward is usually proportional to the value, but it&#x27;s something to think about). Is it essentially the equivalent of rent-seeking - that is, they get their hands on the resource first and then sell it to others? Or perhaps it&#x27;s simply the free market, but working on a timescale of microseconds, where efficieny does&#x27;t really benefit a society of humans that live on timescales orders of magnitude larger.<p>Finally, there&#x27;s the concentration of wealth that results from these activities, which is a serious concern.<p>(I&#x27;m not saying everything everyone does must contribute to society, or that I&#x27;m a saint who lives on nuts and berries and tends to lepers, but it&#x27;s a consideration.)