There's a particular bit of wishful thinking endemic to software project managers, in particular: the belief that almost everything useful is also predictable,

There's a particular bit of wishful thinking endemic to software project managers, in particular: the belief that almost everything useful is also predictable, and that what's left accounts for only a tiny fraction of the overall effort. A bit of reflection should make it obvious that the opposite is true: if it was so easy, somebody else would have done it before. Yet, like every 15-year-old who believes in their heart that they'll grow up to be rich and famous, the manager always assumes that they're just the first person to think of cloning Facebook.