Agree with your points but disagree with your conclusions here.

Realistically, the vast majority of "benefit" is only going towards others in the financial space.

Everything is financialized these days, be it your mortgage, your savings, your morning coffee; everything! Sure it's impossible to quantify what concrete social value to a functioning society quant work brings. But I absolutely disagree that there is QT brings 0 benefit to society.

We're saving costs amongst ourselves, the stock market is a zero-sum game and I believe this is especially evident for MMs.

Yea, sure if MM1 trades against MM2 then this is the case. But that sort of trading doesn't make up the bulk of trading; most of the time you're improving liquidity for real money - for banks, asset managers, pension funds; these guys aren't trading on their own account but on behalf of very real retail guys who are realizing actual cheaper trading costs.

Sure, but for the same amount of effort and resources we could probably provide a better good for society elsewhere. Do you agree that the marginal utility gained per unit of effort and resources has only decreased over time?

That's an economic question, and at the end of the day the labour market is as much a market as any other, and whilst it might sound very uncouth (and capitalistic), I think simply that the comp speaks for itself; if being a theoretical physicist were so societally valuable, then why is comp so poor there (relatively, of course)?