They were listed in the same paragraph because they were examples of people who are widely considered to be "geniuses", but who either held menial jobs at one point in their life, or who weren't "successful" (in the common sense of the term) at one point in their life (in Van Gogh's and Kafka's case it was at all during their life, in Einstein's and Wittgenstein's case, during significant portions of their lives, though Einstein was certainly vastly more successful than any of the others during his lifetime).
The OP was talking about one point in the Target employee's life, the point at which he was a Target employee and an LSAT teacher, and he seemed to be judging solely based on job titles. That's a very myopic, and I would contend, unfair vantage point from which to judge a person's life, contribution to humanity, or achievements... as the examples I mentioned (and many others that I didn't mention specifically) demonstrate.