>Is that path accessible to everyone
I don't think so, although I feel like it is sometimes constructive to believe it is (from a personal perspective).
From what I know, the 10 hours a day usually starts before teen years (it is common for musicians who reach virtuoso level to achieve "university-level" technical ability before they are 10 years old). For instance, amongst the musicians I've known, playing all Chopin Etudes or Grieg Concerto by 8 years old isn't particularly outstanding - these are easily Diploma level 2/3 works.
What I also know is that a lot of these musicians typically have a lot of financial backing - finding a good teacher and a good instrument is expensive! Unless you're a 1 in a 100-million talent, you probably won't find a sponsor as a child...
Lang Lang is probably one of the musicians I can name who wasn't particularly wealthy growing up...
On the subject of survivorship bias - almost certainly this reeks of bias, we never hear of the dropouts... Presumably those that stay healthy/positive wind up in session-gigs and education.
>I've known a few very skilled musicians
I can't say much about your friends, although my anecdotal intuition feels that virtuoso* musicians' success sits on a pareto distribution: those in the top 5-10 of their individual field are lavished in concerts, records and money. The 11-200 are probably reasonably comfortable and the 201 onwards start having to worry about making ends meet.
This is true for other skill-based professions - look at tennis players for instance, they struggle to break even on their livelihood if they're outside the top 200.
An observation a pianist once told me that scared her was that every few years there's a new star who wins the Chopin or Tchaikovsky competition who then robs the limelight. Adding to that, as musicians have a long career you have a long-tail/pyramid effect where the base is constantly growing, but the rewards are fixed if not shrinking.
*(where a major factor of their success is technical skill)