She might be. She's in private practice so she's got a big overhead. I don't know what her practice, payer base and hours are like.
You're right, everyone does pay taxes. Just wait until you start paying yours at physician brackets and suddenly you'll see the truth in my statement. That huge salary that gets quoted actually isn't that much to spend. Next, retirement: physicians are usually 10+ years late to the retirement game, therefore if you don't want to be working when you're 60 or 70, you need to invest a big portion of your pie into retirement which makes for even less disposable income. Next, loans: loans are not income based. Loans are loans. You take this much out you pay this much back. You may be talking about federal forgiveness but not everyone qualifies for that. Especially not private practice so that's not applicable in this thread. Lastly, malpractice is usually paid by your employer, not necessarily the hospital. If you're self employed, guess what? That's you!
You have a lot of misconceptions about what being a physician is really like financially (which is fine). Hell I was probably the same way as a premed and in med school. When you get to the other side though you realize the best major in undergrad is actually economics.