That sounds about right. A small number of people with inside info are gaming the system itself and everybody else is just gambling.
https://ideas.repec.org/p/pra/mprapa/24487.html
https://arxiv.org/abs/2501.03658
Notably market makers can make money off the noise injected by uninformed traders but would not trade with informed traders if they could help it. (Look how “sharps” are kicked out of online sport books.)