This is where the Econ 101 naiveté of your comment goes completely off the rails. I am wondering if you are trolling.
- A vet certainly does not need to be a "great" profit source for PE. I genuinely can't believe you'd say that with a straight face. If it barely breaks even and the owners end up flipping the assets and real estate, that's a win.
- The obvious reason PE has stepped up their investments in pet care is that COVID led to a huge spike in US pet ownership. In about 5 years this spike in vet demand will fade. When that happens, these firms will wring their investments dry before moving on, leaving debt-saddled clinics behind. You can't just ignore the actual economic context because you found a fact-free explanation that high schoolers find convincing.
- in general it might be barely profitable to run a good vet clinic, but highly profitable to run a terrible clinic. I doubt emergency vet medicine is very profitable. You can't just assume PE runs the clinics the same as a vet-owned clinic. In fact the article makes it clear that this is not the case.
- There is just a total lack of humility from you: being smug and ignorant is a bad combination. Sure, the article is full of people complaining about specific PE-owned vets, and the comments on HN are full of people complaining about specific PE-owned vets.... but maybe if they understood the law of supply and demand, they wouldn't be so upset.