Because the money isn't good right now. Before PE, vets were making $60k out of school and maybe $100-120k after 10 years. Now, PE has caused a huge run up in salary because people aren't excited to work for them. New grads are starting at $100k and experienced vets are asking for $150-200k. While there's a glut of PE money they're financing all this and hoping to make it back somehow down the line. But a doctor-owned clinic would have a start up cost of probably $750k to $1M (or more) and that would be financed at 8-10% over 10-15 years now. They'd have to rent and build out a space or buy it on 25 year amortization. Loans have a personal guarantee.

You generally can't solicit your old clients so they'd have to choose to find you and you'd have to build the rest of your practice. Lots of risk.

You could expect to pull the new grad salary and use the rest of the cash flow to cover your loan. If things go well, you could be making a good salary and sitting pretty after 10 years. Or you might underperform and find yourself struggling to pay your staff while taking a minimal salary until you can get out from the loan.

If PE clinics underperform, they just shut them down and write it off.

I’m an ophthalmologist. The answer is that junior partners are brought on at a below-market-rate salary with the promise of future equity (usually under false pretenses) in the practice and a super restrictive non-compete agreement. The senior partners then take their golden parachute and sell-out the field and the junior partners to the PE finance bros. One then has to choose between selling their house, uprooting their family and taking the financial risk that comes with starting a practice in a new location (due to the non-compete) or continuing to work for the PE firm as they devolve to more and more unethical business practices. Eventually your choices are either go into solo practice or work for PE