PA (physician assistant) vs NP vs Education (assumes people don't start in other career tracks or other jobs). For reference, CRNA (nurse anesthetist) has similar training time at NP but the salary is MUCH higher
PA - Pre-requisites for PA school
NP - Halfway thru nursing school for RN degree
MD - Halfway thru undergrad for Bachelors degree (pre-requisite for med school)
PA - start in PA school
NP - finishes nursing school with RN degree (can choose to take time off and actually work as RN for over 60K per year)
MD - finishes undergrad (hopefully), starts APPLYING for med school --> needs $$$ for applications and travelling to interviews, over 25% of med school students have Masters and/or PhD's and/or other degrees BEFORE starting med school. But for sake of brevity, assume best-case scenario that this hypothetical student goes straight to med school
PA - can start working, may do an extra year of "internship" which is required for certain fields (surgical PA, ICU, etc)
NP - starts first year of NP school (already has RN degree)
MD - starts first year of med school
PA - has been working for 3 years (2 years if he/she did an internship)
NP - start final year of NP school
MD - finishes 3rd year of med school, still 1 year to go
PA - has been working
NP - has been working and easily has been earning over 60K during first year of work (because that's what an RN makes and NP's are paid much better)
MD - starts final year of graduated med school, start looking for residency --> spend money on application process and travelling to interviews. This assumes that the MD didn't get a dual degree (MD-MBA, MD-MPh, MD-JD, MD-PhD) which is required for certain areas (administration, research, etc) and can add 1-2 years to med school.
PA - working
NP - working at 80-100K per year
MD - doing residency and earning 50-60K per year while working 50-80 hrs per week --> please note that this is bare minimum of residency for physicians and that the average residency is actually 4 years and some of the surgery programs are 5-7 years (some academic centers require residents to take a year off clinical training and do research work and get publications)
PA - working
NP - working, salary is probably ~100K per year at this point
MD - starts work, although > 70% will do a "fellowship" which is an advanced residency that lasts 1-3 years (ABSOLUTELY NECESSARY for some of the specialized fields) where salary 65-80 K per year (comparable to senior RN or newly-minted NP)
In reality the MD will probably be 31-32 before he/she actually starts working. The NP will have already earned over $300K and the CRNA has earned over $400K at this point.
A primary care doctor's salary is comparable to CRNA, so a primary care doc will NEVER catch-up to the CRNA in terms of money, but this primary care doc should surpass the NP in terms of $$$ earned sometime in the late 30's or early 40's.
A specialist, who can earn over 250K (if they're investing their money and/or they have administrative duties at their hospital/clinic they can earn upwards of $500K) will surpass the NP in his late 30's and the CRNA in his early 40's.
As you told the young man: Go the NP route unless you plan to specialize, become an administrator, or really have an calling to be a doctor.
Lastly, for PA's and NP's who want to go to medical school to pickup some extra training (because there are some things that only MD's can do), most medical schools have accelerated programs that let the PA's and NP's skip entire years of medical school. Additionally residency would be a breeze for these folks and they would have the opportunity to pick-up the actual nursing shifts on their weekends off.