[astrange]

You can’t have a monopoly in an industry with no barriers to entry. Cartels aren’t stable because every newcomer has an incentive to defect.

[verve_rat]

It costs more than zero dollars to set up a new vet clinic. I'd bet a bunch of the shit they need is really expensive.

[pclmulqdq]

Capital alone can't maintain a cartel. Investors can partner with doctors to set up a new vet clinic to help break the cartel, and there are significant rewards for both. In turn, the competition lowers prices across the board. Cartels are essentially a prisoner's dilemma without rules (like licensure) enforcing them.