According to the school curriculum, and Wikipedia, the Earth has the shape of an oblate ellipsoid. Many perceive this information as an indisputable fact, and do not even try to check it in practice. Nevertheless, common skepticism still alive on our planet
If a person tries to argue on rational grounds that it is reasonable to be skeptical of an oblately-spherical Earth because they don't "check it in practice," then in order to be consistent he needs to be skeptical of a litany of other facts he hasn't personally verified.
Some examples may include: the existence of any country they haven't been to; molecules and atoms; bacteria; photons; his own mortality; any image/photo/video of any event they didn't personally witness; etc.
It's easy to see how consistent application of such extreme skepticism would be detrimental to him.