There's the saying "science advances one funeral at at time."
'‘A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.’ This principle was famously laid out by German theoretical physicist Max Planck in 1950 and it turns out that he was right, according to a new study.'
Also the story of Ignaz Semmelweis who discovered that if doctors washed their hands it reduced deaths during childbirth - but for a variety of reasons his findings were resisted.