This Bloggingheads clip highlights that the space program has been very disappointing. I remember all the accolades for astronauts and our space program as this was not only dangerous and difficult, but supposedly really important. It would supposedly help us manufacture drugs, create moon colonies, etc. The whole manned space flight program since Apollo has been a failure, producing absolutely zero new scientific theories or data.
In announcing the first rough draft of the human 'book of life' at a White House ceremony in the summer of 2000, President Bill Clinton predicted that the genome project would 'revolutionize the diagnosis, prevention and treatment of most, if not all, human diseases.' That hasn't happened, and is doubtful.
I think this highlights the problems predicting the future in anything, from dividends, to science, to politics. It's easy with hindsight to see how irrational past beliefs were, and it would be interesting to know how much of conventional wisdom was held by people who had a lot of common sense. I have a suspicion the seemingly bad predictions were from the media, which is populated by journalists, who as a class I find rather ignorant (when I was a TA at Northwestern which has a 'good' journalism school, we had big intro classes and they listed the colleges the kids were from, and they always followed the same g-loaded order: Engineering, Arts and Science, Journalism).