Where is it that you work?
I'm not all that familiar with PMHNPs, but everywhere I look online does not have pay levels near what you are quoting.
Psychiatric Nurse Practitioner (NP) Salary
Psychiatric Nurse Practitioner Programs (PMHNP) | Jobs and Salary Information | Education
https://www.nursepractitionerschools.com/faq/how-much-does-a-psychiatric-np-make
The mean is typically ~$100,000/year nationally, with the 90th percentile for earners being less than $130,000/year. Even with bonuses, the $140,000/year figure you quoted for starting pay is still at approximately the 90th percentile for earners nationally. As for those PMHNPs you know earning over $175,000/year, that's still substantially more than the 90th percentile for those late in their careers. I'm not saying these figures are impossible, but rather, they are anecdotal and substantial outliers at the top of the pay scale and are likely regionally variable. Thus, I don't think they are appropriate to use for advising potential PMHNP students.