They don't have to rant daily about this. For every successful Thai restaurant, I can show you 4 that failed [or more].
There are many ways to Rome, 37 signals likes to walk to Rome while others take a lot riskier route. For each his own.
One, this wasn't a rant. It was neither bombastic nor over-emotional. It seemed to me to be wholly uncontroversial. If anything, the relatively conservative steps he advises (starting a business with only moderately successful aims) seem downright boring.
Second, the failure rate for new businesses is not 80 or 90%. Even a little bit of googling would put that to rest. To wit:
http://www.businessweek.com/smallbiz/news/coladvice/ask/sa99...
And, as the article points out, the very buyout scenario that many YCers (HNers, really, unless you've been accepted) dream of would be counted among the failures. Fewer than 10% of these failed businesses were the dreaded bankruptcies.
Seriously, nothing to see here. And if any of you really were convinced that you've got a 90% chance of failure, you would stop complaining about 37 signals "rants" and get to work shoring up your (apparently) failing business.
Besides, show me 1 successful business and I will be able to show you 9 that failed (if the 1 in 10 success statistic is correct) - most businesses will fail, not matter which way you do it.