We can't all work for Bloomberg stanimir :)
fanatical Ruby developers who believe the language's syntax, its high developer productivity, and its overall philosophy far outweigh any performance disadvantage it might have compared to other languages.
Well, they built it in Ruby, and everyone jumped on board it. You are positing that had they built it in Java from the start, they would have built it just as fast, and people would have jumped on board it just as quick, just as quick.
Ruby is no good for prime time anyway really, it allows too much hackery and punctuation - check out some of why_'s DSLs written in ruby. Write in python, if it is too slow, rewrite in C. C aint hard.