Historically, science and technology have gone along many routes which turned out to be dead-ends.
Science has many discredited theories and obsolete paradigms such as alchemy, phlogiston, universal ether, and more. They failed the reality test and were cast aside, occasionally turning up in fantasy stories and crackpot websites. Some scientists use science to explain/interpret social and cultural phenomena. Sam Harris, for example, says (completely ignoring the spiritual, cultural and social aspects) the religion “is indeed failed science” and expresses hope that information, education and science will rectify this situation. In the modern world even renowned scientists are prone to making claims and predictions, which cannot be substantiated. An interesting case in point is Paul Ehrlich, a world-renowned entomologist whose failed predictions about environment (for example “There is no evidence that global warming is real“) are still resoundingly discrediting relevant scientific research and available empirical data. There are even cases (controversy surrounding discovery of element 118) when scientists deliberately fabricate fake data to support their theories and claims.
Technology has a bit more wiggle room but is still full of false/failed predictions and intentions. Some technologies were perfectly viable from an engineering standpoint, but either couldn’t compete economically or never really had a market. The canonical example is airships. With abandoned technologies there’s always the suspicion that if things had turned out differently we might be driving atomic cars or be regular tourists on the spacecraft Cycler commuting between Mars and the Earth or some other high-end, futuristic sci-fi-inspired gig. Douglas Self‘s Museum of Retro Technology contains information on dozens of devices, which existed, but never became part of everyday life.
Failed technologies are different from completely bogus technology. We’ll never get power from a Keely Motor and we will most probably be unable to make mainstream steam-powered airplanes because they either had high costs related to manufacturing or unprepared markets or could simply not compete with more conventional designs.
But all these false roads and blank directions were not taken in vain. If you take a look at major inventions and discoveries in science and technology you will see that most, if not all, happened by merry happenstance (radioactivity theory by Marie Curie), unanticipated development (Arpanet and Internet) or in the course of pursuing a plainly different objective (serendipitous case of discovering penicillin by Alexander Fleming).