Another factor could be familiarity, by now people are so used to seeing C like syntax, any things else would feel automatically difficult attracting huge investments in time to learn.
Also if most developers have to learn lisp, there have to be enough jobs.
Right, good point. Sort of a chicken-or-egg situation.
Also, this reminds me of Paul Graham's famous essay, Beating the Averages [1], about why and how he and his co-founders used Lisp at their startup Viaweb, which was later acquired by Yahoo! for ~40 million USD, IIRC.
I think it was this essay, along with his other one about the first summer school for founders (which later became Y Combinator), that attracted the attention of a lot of developers (some of whom later became successful YC applicants) and helped both YC and HN take off.
Also if most developers have to learn lisp, there have to be enough jobs.