Why is it that the vast majority of predictions of the future are generally wrong?
If anyone knew the answer to that question they would be able to use it to make “generally correct” predictions about the future, in which case you wouldn’t be asking this question in the first place.
Then again, perhaps those who can successfully predict the future simply find it more profitable to keep their methods to themselves.
Have you ever heard of the butterfly effect? It has to do with weather forecasts but would be applicable to any type of future forecasts.
Of course, you may believe in Jeanne Dixson or Nostrodomus (sp?) in which case you won’t believe anyone that the future can’t be predicted.
I interpreted the OP as relating more to the “within 20 years science will be able to do X”, or “every home will be computer controlled”, or “everyone will have a surplus of leisure time due to technological change” type predictions, not the Nostradamus type.
I suspect one reason that predictions about the future are often horribly wrong as that they usually assume the best possible circumstances and don’t necessarily take into account any negative effects a new technology or similar may have.
In some fields - medicine is one which springs to mind - at the same time as we are discovering new things, we’re also discovering just how little we know. Some things won’t pan out at all, others will prove too expensive, yet others will lead us in entirely new directions.
Predictions, are essentially just “best guesses” based on the information we have, and the assumptions we make, at a given point in time - daily, we discover new things which may contradict that information and shatter those assumptions.