Chris Klein...was it just the money?

why is it that there are test drivers like Wurz and Marc Gene, who's capable of running at least mid-pack ('03 Monza), still testing cars waiting for a permanent driver's seat while Chris Klein can snatch up a seat w/ Jaguar out of the blue. Was it the money/endorsement he brought in, or was he actively pursued in pre-F1 racing? OR...do the test drivers just prefer testing over racing?