Because the FDA and drug companies are always right and have your best interest at heart.
From the list of withdrawn drugs. And don't tell me "withdrawn" somehow means the drug companies and FDA were doing their job. There are plenty of poison drugs on the list that Rezulin is on.
========
"Parke-Davis/Warner Lambert submitted the diabetes drug Rezulin for FDA review on July 31, 1996. The medical officer assigned to the review, Dr. John L. Gueriguian, cited Rezulin's potential to harm the liver and the heart, and he questioned its viability in lowering blood sugar for patients with adult-onset diabetes, recommending against the drug's approval. After complaints from the drugmaker, Gueriguian was removed on November 4, 1996, and his review was purged by the FDA.[8][9] Gueriguian and the company had a single meeting at which Gueriguian used "intemperate" language; the company said its objections were based on inappropriate remarks made by Gueriguian.[10] Parke-Davis said at the advisory committee that the risk of liver toxicity was comparable to placebo and that additional data of other studies confirmed this.[11] According to Peter Gøtzsche, when the company provided these additional data one week after approval, they showed a substantially greater risk for liver toxicity.[12] The FDA approved the drug on January 29, 1997, and it appeared in pharmacies in late March. At the time, Dr. Solomon Sobel, a director at the FDA overseeing diabetes drugs, said in a New York Times interview that adverse effects of troglitazone appeared to be rare and relatively mild.[13]" https://en.wikipedia.org/wiki/Troglitazone