Many people many times in history have been looking for the curvature

Many people many times in history have been looking for the curvature. The result is always the same - there is not such measurable, man could only "see" a faked one due to perspective, but factually there is nothing there to detect. How come only the same people see it, who have a budget anually around 24 BILLION dollars? Could there be a catch here? You dont say. Research flat earth.