20-Year Prospect
As mentioned previously, there's a real shortage of brain surgeons in the U.S. Between how long it takes new surgeons to get qualified, and the fact that old surgeons are retiring early, the numbers just aren't adding up. That's great news for you: you won't have to worry that other neurosurgeons are snapping up all the jobs while you're in school.
Since the shortage isn't predicted to ease up anytime soon, it should be pretty easy to find and keep a job if you're good at what you do. People aren't going to get fewer brain problems just because there aren't enough neurosurgeons to go around, and there's no way you'll have to switch careers because you're just not making enough as a neurosurgeon.
Those student loans will practically vanish overnight when you're pulling in hundreds of thousands a year. In fact, there are really only two reasons why you might not last in this career: you're really bad at being a neurosurgeon; or the stress gets to you.
As a brain surgeon, you'll have to keep up with all the latest discoveries, developments, and technologies. Medicine is advancing by leaps and bounds right now, and there's no telling how new developments will affect the average neurosurgeon's day-to-day. It'll be a lot of work to keep up with the times, but you can totally handle it—you're a brain surgeon. They only let the really smart folks take a knife to patients' noggins.