Then when they're 50 they'll look back on stuff they thought was fine when they were young, and is bad now. If they're introspective they'll look at the stuff that their parents or grand parents or further back thought was fine and turned out to be bad. As people say, it's easy with hindsight and it's really hard in the moment. Many second and third order effects aren't obvious or testable. Then add profit motive. The real question is do you change when you realize you were wrong or double down.