Sure, the odds in Classics (and academia generally) are stiff -- but are they really any better in other professions that are intellectually demanding and/or tend to be viewed as prestigious? Do you imagine it's any easier becoming a journalist for a major newspaper or magazine? Does everyone who wants to work for a bank or consulting firm end up getting a job in these industries? And how many failed entrepreneurs do you imagine are there for every successful one? Even in the case of law school (which, incidentally, tends to be a popular option for PhDs who find themselves stranded on the job market), a top JD program no longer guarantees gainful employment, and a precious few eventually end up becoming judges or partners at major law firms.
As for top programs and their placement rates, I think it's getting things backwards to believe that a program has some binding obligation to be able to place you in a TT job. When I look at a department's placement record (and yes, no one's is perfect -- though some of the best, like Berkeley, Stanford, Princeton etc. seem to be able to get 4 out of 5 graduates some form of employment in classics straight out of the gate), what it tells me is how strong some of their middling to best students tend to be, which is really a function of how tough their standards of admission are. So, if I get into a dept with a strong placement record (i.e., a mixture of VAPS, postdocs and tenure-track offers for 75%+ of alums), all that allows me to be confident of is the idea that I'm *expected* to turn out to be as strong as some or most of their candidates -- but that certainly doesn't mean I'll be guaranteed something like the nice TT job last year's strongest ABD landed, etc.
In the end the onus to succeed is one's own alone; a strong program can only give you a few advantages which you may or may not be able to use to the full. Personally I've made the choice after much reflection to accept this risk and to take my chances in the profession. Fortunately I'll have the help and support of a top program in doing that, and believe me, I wouldn't be making this gamble if I hadn't managed to get into a top program. But now that I've given myself the strongest possible start, I'll take my chances, and enjoy the next 5-6 years doing what I'm passionate about.