There's a limited number of spots at the upper echelon, so it's natural that they go to talented people who are most passionate about that kind of work (which t

There's a limited number of spots at the upper echelon, so it's natural that they go to talented people who are most passionate about that kind of work (which translates into willingness to work longest hours and other personal sacrifices). It's a very fair system - let's say the world has money for a total of 1000 string theoretists, so it makes sense to only assign the jobs to geniuses who are also in love with string theory, as opposed to say smart people who are kind of interested in physics.