A counter argument: if they are getting the PhD as evidence of mastery in a topic they love, it doesn't matter what comes after it, unless circumstances will force them to give up what they love until they die.
The intrusion of bad "circumstances" is the norm in academia. Actually, it's the norm in life, but academia is set up in a way that makes it nearly impossible to recover.
Also, the "love" people have for a subject or field is highly conditional (not that it should be any other way; that wouldn't make sense). This is mere attachment. Unconditional love for something so abstract probably cannot exist, and if it can, is not desirable in any case. It's legitimate to be intellectually fascinated by finite fields or 19th-century literature, but to say that one loves these things is a stretch. A person who's capable of developing a fascination with X is equally capable of finding a "love" for Y; that's a core trait irrespective of niche-bound particulars.
So when someone is forced into an unappealing niche by academic politics, lives a crappy lifestyle on account of the university's stinginess, and has a fractured family life due to overwork and constant geographic uncertainty, all while having to cope with distracting administrative and bureaucratic chores, it makes sense that this "love" of subject matter would disappear entirely. Most people realize, upon growing up, that they love their families and decent lifestyles more than intellectual abstractions.
In my academic career, I've worked on foundations of quantum mechanics, numerical scattering theory, and now I'm working on medical imaging and computational geometry. On the side, I'm doing some web development (database stuff and also business optimization). I could do basically any technical work and enjoy it. There are some things I like slightly more and am moderately better at (not always the same thing), but those differences are marginal.
To answer your specific question, it's definitely a place worth checking out. There are great CS theory/math people here. The culture is friendly but a bit isolating. You will need to actively work at meeting people you don't directly work for.
I don't disagree with you, although that doesn't contradict what I said: I use "love" in a very strict sense, in the same way you use it in the unconditional sense.
So another issue I didn't make clear was that many people who declare their love for a subject don't really know to what extent this love stretches. In my book it means being alive implies doing X, until life ends.
The intrusion of bad "circumstances" is the norm in academia. Actually, it's the norm in life, but academia is set up in a way that makes it nearly impossible to recover.
Also, the "love" people have for a subject or field is highly conditional (not that it should be any other way; that wouldn't make sense). This is mere attachment. Unconditional love for something so abstract probably cannot exist, and if it can, is not desirable in any case. It's legitimate to be intellectually fascinated by finite fields or 19th-century literature, but to say that one loves these things is a stretch. A person who's capable of developing a fascination with X is equally capable of finding a "love" for Y; that's a core trait irrespective of niche-bound particulars.
So when someone is forced into an unappealing niche by academic politics, lives a crappy lifestyle on account of the university's stinginess, and has a fractured family life due to overwork and constant geographic uncertainty, all while having to cope with distracting administrative and bureaucratic chores, it makes sense that this "love" of subject matter would disappear entirely. Most people realize, upon growing up, that they love their families and decent lifestyles more than intellectual abstractions.