The problem is that a lot of people have a very binary view on life. Either something is a complete success or a complete waste of money, rarely do we accept that most projects fall somewhere in the middle.

And even worse, they don't think probability is a thing. If something happens, it was certain to happen and we just failed to predict it correctly.

So when someone predicts something will happen with a 90% probability, and then the 10% chances happens and the predicted event does not happen, people will talk about what a bad prediction that was and how they were clearly wrong.

It's the same logic that causes people to say vaccines don't work because they don't stop a disease with 100% effectiveness, or that there is no point to wear a seatbelt because people still die while wearing one.