Considering all of the uproar caused by the Newsweek article, if people knowing you have bitcoins puts you in danger, then I'd say it's not a currency I want anything to do with.
Yeah, if everyone knew I had £1,000,000,000.00 hidden under my mattress (and some mattress that would be), then I imagine my life might be under a little more threat than otherwise too.
Err, it is widely known, google "world's richest people". The difference is, as your sibling post pointed out, those people don't have it hidden under a mattress.