It is more expensive to open a clinic than a restaurant, with the costs being anywhere from $500k-$1M. The main difference between the two is that the vet clinic has higher running costs aka salaries in the early years before the practice takes off. For restaurants, it’s relatively lower (staff salaries and produce) if the demand is lower.

500K-1M seems about 1-3x a typical restaurant. I'd also be surprised to learn that running a vet is more expensive than a restaurant. The margins are seem like they'd be way lower in a restaurant.

Other than the doctorate, of course.

Presumably there is already a supply of licensed veterinarians, unless the PE vet practices are hiring unlicensed practitioners.

How many of them have easy access to a million bucks?

Probably most of them. I don't think the limiting factor is access to capital, but rather the risk.