Maybe that's the average trajectory in the US (and not for a successful scientist since she fails in the end!). But let's not forget that the US is not the only place where a scientists can find a job. There are many research institutes or universities in the world where someone with a PhD from Stanford and a postdoc from MIT (and less than that) could find a stable position.

Besides, one has to consider the other options available. Would the person in your example be happier had she taken a different path? who knows.

I wouldn't discourage people to try and work in that field if that's what they want to do.