I am not an NP, but I have interned for an opthalmologist who did his MD/MBA dual degree and owns his own clinic which has been open for about 3 years. He said he makes a lot less than he would just working for someone because he has to pay staff (2 medical assistants and 1 front clerk), rent, medical supplies including the upfront cost of medical equipment, and invest money into the business (marketing, decor, upgrades) before he takes the rest as income. His revenue also depends a lot on the type of cases as most of his patients come from medicare which pays less than a patient who has private insurance. Revenue is also impacted by no-shows and the variability of the amount of patients he sees as it depends on things out of his control (marketing, scheduling, time efficiency). He also does his own billing with his wife who is an ER physician which is a lot of time commitment. He works 8am-7pm 6 days a week and is the sole provider in the clinic.
Although this is different from your situation, I just wanted to highlight some of the challenges I've seen for a practitioner to own their own business.