This is what you get when scandal after scandal happens to public institutions. People go flat earth most often, not because of the "science," but because they do not trust the government for honesty.
This also happens whenever there is an apparent "win" even if it isn't quite so. For example, when a judge last week ordered federal Fluoride standards to be re-examined. It doesn't need to be a total vindication of the conspiracy theorists, for trust to be substantially damaged. Same for the Iraq war, with "weapons of mass destruction" - imagine if your child died from that lie. Repeat this every year, in multiple institutions, for 20+ years straight; and yes, observant people might well think that everything the government has ever said is a hoax. It's not about the science, or their ability to track truth from falsehood, but their reactionary hate of anything the institutions say.