Text: and some of them don't realize that they've made a mistake and so uh you know a lot of energy and uh a lot of work and so forth uh goes into building something only to discover it doesn't work
Entailment: Some people don't realize they've made a mistake, and then a ton of energy and work goes into constructing something just to see that it doesn't work.
Contradiction: Mistakes are never made, and the finished products are always completely functional.