That's what a dream is, though, isn't it? You decide that something matters to you. Sure, you can change your mind, but then the dream goes away, and it hurts to have your dreams crushed. I think that's really all he's saying.

My thoughts exactly. Sounds like he matched up with a pretty great advisor (good person, good manager, helpful, smart), worked on interesting problems, made progress on some, published, and graduated. To boot, when he decided to move on, his physics skills made him highly employable in the financial industry. I'd call that a success story as far as grad school goes.

Funny thing is that when he asked Rajeev why he had failed, Rajeev had probably been asking himself the same question for years. A lifetime dedicated to cyclotomic fiber bundles that will probably end up in the dustbin of history.

If your only measure of success is to do something truly transformative, well, you've got Copernicus, Newton, Einstein, and then everyone else who has tried and failed, so good luck. Wall Street was probably the better choice. And it could have turned into a Swiss patent office thing that formal academia would have denied anyway.

Grass is always greener on the other side.