The cost of medical school is over 200k (mine was a blessed ~250), at an interest rate generally about 6.8%. This doesn't account for loans generally needed to pay for living expenses (assume another 50k for four years' rent), mandatory licensing exams (5k), study materials, etc. Medical school highly favors people that went to private undergraduate educations - add some number of thousands here. And on average, about 50% of medical school applicants these days have some sort of Master's degree - again, favoring private education.

When I went to school, a few people had wealthy parents that made the debt issue disappear. Most were about 300k in debt when they graduated. I had a cheap undergraduate, but a private master's, so I came out of school at about 350k, with my interest rates ranging from low-6's to high-6's, with one "small" loan (~80k) at 7.8%.

By the time you hit residency, some folks are still single, but most have at least a serious partner, or are married, plus or minus a kid. When I hit residency I had a wife and a kid; my buddies were all married, getting ready to have a kid. They'd all have one by their second year of residency.

So, at this point, you're making about 50k a year, your spouse is probably making something similar or less, while effectively being a single parent. They probably still have school loans of their own, never mind carrying the cost of supporting the entire household. They are not servicing your debt. Kids are expensive, and the childcare you have to pay for as effectively-a-single-parent is even more expensive.

If you're single, depending on cost of living in your area, you're either putting off all your repayments (taking income-based repayment schedule) and living with a few roommates, or you're actually taking more loans to make it through.

Your training program will pay for your licensing exams in residency, and cover a decent portion of the cost of attending academic conferences. You won't spend a lot in this category unless you're aggressively academic.

It is not uncommon at this point to finish your residency training with more debt than you started - if you went in with 350k, it would not at all be surprising to be >500k at this point.

Now you go into practice. Fresh out of residency, general internal medicine, depending on your region, expect to make 180-220k. You're also at this point in your 30s, you've got a kid or two, your debt, likely a good chunk of your spouse's debt. Most available jobs are in reasonably high CoL areas, or they're out in the middle of nowhere. CoL isn't entirely up to you - most residencies are in high population density, high CoL areas. Residency is where you form all your professional connections; it's very hard to land a job outside of the zone of your residency, unless you're willing to go to an extremely poor backwater that just can't attract a physician at all.

Some docs at this point are willing to continue living like they're paupers, keep their family penned up inside a tiny apartment, driving their old beater. If that's the case, you take your 220+60 = 280k/yr household income, call it 200k after taxes, and devote 100k of it to debt servicing. You can pay off your loans in six years.

The truth is, though, that after you've lived like a pauper for your entire twenties and into your early thirties, and you've got kids, and a spouse that has supported you through all this garbage, and all of your non-medical friends have long ago vastly outpaced you, and you haven't had a decent vacation in ages...

Some new docs go overboard and start spending like mad.

Most don't. All the folks I went to school with came out and got reasonably nice apartments, so that at least their kids could each have a bedroom, got a slightly-better-than-entry level sedan (Nissan Sentra or Nissan Altima was de rigeur), bought a few suits so that patients would stop confusing them for students, took their spouse on vacation, and started servicing their debt - most taking a 30-year plan, and adding pre-payments. Some folk could pay it off by the time they were 50. Most couldn't - once they realized they also had to start putting money into their kid's college funds, and hopefully build something like a retirement fund, well...

I entered residency with 380k of loans (I paid off undergrad by attending a cheap public institution and working it off, but I got a Master's in a private school, though they gave me a solid merit scholarship, and then... med school.) My wife had about 80k of her own loans remaining; luckily, her parents paid off her private undergraduate debt, but she had grad loans to pay. We had one child, and were planning on two - financially timing a kid is hard, because the counterpoint is the rapidly increasing chance of birth defects with maternal age. I was 32. (I worked for a bit between Master's and Med school). We lived in a 2br as far from our intensely-high CoL area as we could tolerate commuting to. Want to picture commuting an hour in each direction when you need to be in by 5:30a and (hopefully) leave by 6:30pm? Fuck. We drove a Nissan Altima, because the area we lived in (that far from the city center) was not public transport friendly. I was lucky, though, because my wife was a high-earner. We still managed to burn through her income on a monthly basis, but it meant that she was able to service her debt on a 10-year repayment plan, and when she got bonuses from work they were put towards my loans.

We were moderately disciplined. I wasn't a martyr; we bought organic fancy groceries for our kid (not for ourselves; we had "organic strawberries for baby and whatever random berry was reasonably cheap this week for mom and dad"), we went on a cheap vacation once a year; we went out once a month.

I got into residency commuting distance from a low-compared-to-where-we-were-before CoL area. We rented a 3br apartment for less than we were paying for our 2br before. My wife had to switch to a lower paying job, because she couldn't keep her old one remotely. Much lower. Our QoL went into the shit, and by the time I graduated, our collective debt had barely budged. Childcare expenses reigned.

I expect I'll be paid off by 45. Hopefully in time to start a retirement fund for my wife and I, and a college fund for the kid. In exchange, we will continue living in a cramped apartment and driving the same car I see college undergraduates driving. Or I could lease a nicer car, and mortgage a house, and I'll be paying off my loans well into my 50s or 60s. And of course this assumes I work crazy hours. If I work half as much, I don't pay off my loans in twice as much time - interest will be compounding. If I work half-time, I'll never pay off my loans, never mind put anything away for retirement.