Point by point:
1) It's equally plausible that she saw an episode of some random medical drama and was fascinated with what went on...much in the same way a kid watching a random Youtube video of a Saturn V rocket taking off hits the

...and yeah, of course "doctor" would probably get more of a reaction than "princess" or "dog walker" as a future occupation...but is there a parent on earth that wouldn't react positively to that? I don't even know if that's something the vast majority of parents on this planet would be able to
not react to positively.
2) I don't get the sense that he's bragging - more just explaining the level of genuine interest that his daughter has in cardiothoracic surgery. I put myself in his shoes - if I had a kid who had that interest and they were up at night googling shyt (remember, kids have a
lot more access to information now than we did when we were kids) and told me they wanted to visit Johns Hopkins because they have the best program...how am I
not taking my kid up there for a visit? Kids obsessed with space drag their whole damn families down to Houston to see mission control all the time...
3) If his daughter is serious about all this (which it sounds like she is), why would thinking about residency be a red flag? If you google "cardiothoracic surgeon" this is the first result:
What Is a Cardiothoracic Surgeon?
And here's the first text you see on that page:
"Cardiothoracic surgeons will graduate from medical school and
go on to complete either a 5-year general surgery residency followed by a 2- or 3-year cardiothoracic surgery residency program, or enter into a 6-year integrated cardiothoracic surgery residency.
Some cardiothoracic surgeons choose to do additional training in a subspecialized area but this training is optional with the exception of congenital heart surgery, which requires completion of a 1-year fellowship."
As far as it being a naive goal motivated by money...how do we know that? Couldn't the same sort of thing be said about a kid obsessed with writing software? We don't dismiss kids with that interest as naive wannabe Zuckerbergs, do we?
4) You're going to need to unpack this a little more. Doesn't a kid who wants to be a hedge fund manager need to understand Black-Scholes? Stochastic calculus? Accounting? How would they get into that career without that knowledge? And why would it require "psychopathic work ethic with no burnout tendencies" to learn these things (assuming they've got the requisite intelligence to do so in the first place)?
Edit:
One more thing on #4 - is it so awful if people "slide back to" med tech or accountant from their original interest in being a doctor or a hedge fund manager? Isn't that what happens to the vast majority of people on this planet? Kid wants to be a musician, his band doesn't make it, ends up being a sound engineer or producer...wants to be an astronaut but couldn't couldn't hack college physics...ends up a salesman at Raytheon or ...wants to be a fighter pilot but didn't make the cut...ends up an aeronautical engineer...and so on and so forth.
I just think that's pretty normal and there's nothing wrong with it...