In many cases, poorly planned or haphazard use of medicines have reduced the curative power of once life-saving medicines. The problem has social causes. In poorer nations, patients can't afford the full course of the medicine, or they buy counterfeit drugs. The weaker microbes may be killed by these insufficient doses, but the more resistant microbes survive and multiply. People in wealthy countries have the opposite problem - overuse of drugs.
Medicine is overprescribed and antimicrobials are overused in food production.
Our grandparents lived during an era without effective antibiotics. We don't want the same situation for our grandchildren.