[ReggieCommaRose]

Devil in the details. MMing is conceptually simplistic but the operational costs are huge and are generally getting worse. Making while fighting these costs against competition playing the same game as you turns non trivial real quick.

That said MMs have mostly consolidated heavily over the last decade (due to many firms collapsing against competitors) so in some ways the business has been commoditized. Not sure if true of MMing ETFs as an authorized participant (JS bread and butter) though, idk much about the logistics there.