[wyager]

I used to work there, so with the appropriate deference to that Upton Sinclair quote about paychecks:

Market makers like JS vastly increase market liquidity across all sectors, which is required for modern high-efficiency economies to work. McDonalds prices are possible because there's enough liquidity in corn futures.

More abstractly, high market liquidity corresponds to higher-confidence information about the future, which hedge funds generate (and distribute for a low fee via markets), allowing for more impressive planning ahead.

Also, you know how when you buy stocks it doesn't cost you anything and you often get better-than-public-book execution prices? That didn't happen prior to modern electronic market makers. Multiply that efficiency gain by umpteen trades every day.

In general, "being in the business of making money" inherently requires you to do something useful to get paid, to the extent you're not just abusing a principle agent problem or something. The most credible argument for hedge funds making money without doing something useful is that they're doing cantillon effect harvesting or something. I think that's pretty small overall.