If inconsistency is a virtue, then here goes. I've come to a conclusion, probably as unsurprising as it gets, but perhaps worth a moment's thought.
Namely: Realism is the death of progress.
We've got a summer building project in progress. We did our levelheaded best to budget it correctly, getting contractors to rework estimates—and redesigning accordingly. (And, hey, I was trained as a construction engineer.) All that said, it looks like the $40K ($40,000—sorry, Admiral) project will come in at about $70,000.
The Big Dig in Boston came in about 4 times over budget, as I recall. For the Chunnel, I think it was about 3 times. Etc. Etc. (I won't even mention that the Iraq war, budgeted by Mr Rumsfeld at $50,000,000,000 is apparently at about $1,500,000,000,000—hey, what's a "B" vs "T" in pursuit of ...)
I decided to do a little careless research at a dinner party, asking several people about their homebrew projects. Three questions: How did you do vs. budget for projects completed a couple of years ago? If you'd known the real pricetag when you started, would you have gone ahead? And, in hindsight, was the eventual pricetag worth it?
To Q1, the answer ranged from about 25% over (if you can believe it) to 5 times (which I do believe). As to Q2, 3 of the 6 I queried said "no way" if they'd known what they were getting into—2 others were on the fence. As to after-the-fact satisfaction, 5 said, in effect, "Yes! We'd do it again"—and one said "Maybe, maybe not."
It's obviously dangerous to generalize from such a sample, but my reading of history, business, and in general, says this phenomenon is as ordinary as it gets. Furthermore, in the back of one's mind, one damn well knows that the pricetag will be far in excess of what's planned.
And my point? You'd better have a great number-crunching CFO, but if you let him-her rule the roost, there won't be much left to roost on. Of course I know it's "Damned if you do, damned if you don't." On the other hand, progress hinges on illusion and delusion. As for me, the Cornell master's degree holder in construction engineering, I'd vote yes in hindsight for every one of my major home projects—even if, as is true, they added to my speechifying "nights on the road" tally.
Cherish your dreamers!