I disagree, but hey, I know good doctors. As to cost... Well, an NP makes an average of $105,670 while a FP makes an average of 209K. Let's do some math:
First off, the NP with an average debt load will have student loans of $1017/mo.
Let's run an after-tax monthly income for someone working in, say, Texas.
$6,494.08 is what it comes out to after tax, assuming no deductions (there would be deductions, but we're keeping things clean).
Basic cost of living in the Houston area in a decent spot, we'll say you spend $1,600 on rent/mortgage, $600 on a car/insurance, $600 on food, $400 on utilities/communications, that puts you at $4,217 in total expenses per month. This assumes your single and don't have kids by the way, which jacks up costs by another $1,500... But anyways, that leaves you with a net of around $2,500 you can actually save and invest. You get out of school 4-5 years earlier than the doctor, but that's all you've got to work with. Or $1,000 if you've got a couple of kids and you're cheap about it, less if you aren't.
Now as a physician, you'll pull $12,006 after taxes in Texas.
Your loans will cost you $2,441. You've got the same cost of living as above, which gives you total expenses of $5,641. That gives you a net of roughly $6,350 to save and invest per month, or $4,850 with the kid deduction, certainly a lot more wiggle room financially and a lot more opportunity to actually save and invest. You put in an extra half decade, but you get a better rest of your freakin' life.
That's just the averages though. I think the trade off is worth it.