The Difference Between Sanity and Intelligence

At this point in history, most people acknowledge that polygraphs or "lie detectors" simply fail at their stated purpose: They do not detect lies, but anxiety. On the other hand, there are "intelligence quotient" ["IQ"] tests that are also widely acknowledged to not test intelligence: "IQ tests test what IQ tests test." However, while polygraphs have been removed from almost all legal courts, "IQ" tests are still widely used. Why?... Some may think that "IQ" is correlated with "success" in society, when success is defined as academic performance, job performance and higher income. However, it is well known that "correlation does not mean causation", and if "IQ" does not measure intelligence, then why would it predict "success"?