* yes, I know the happy ended was probably not the real story *
No, it wasn't. Like Torso, I looked up the real versions after watching the film. The elder patient (who was probably the one that inspired the movie) died from a complication from the nearly continual blood transfusions that he went through in an attempt to strengthen his immune system and the younger kid (whose entire life is rather tragic) died after a badly advised bone marrow transplant that was supposed to save him. His final request was to drink a Coke, which he never got to do in the bubble, but his illness was so severe that the docs didn't think it was a good idea and vetoed it. They died at 18 and 13, respectively.
These were kids who frankly were living rather bleak lives and the idea that "It's really all in your head. If you just left the enclosure, you'd be fine!" is rather reprehensible to me. The riffing is fine, but the movie beneath it just makes me madder and madder every time I watch it.