Tell me, is it so easy to circumnavigate a globe that people do it regularly without instrumentation or guaging their position with respect to the stars? Because if they're using instruments or the stars, then I don't see how it's any 'easier' on a globe than on a flat Earth.
Except that on a flat earth once you get to the south pole and start coming back the other way, you'd be strangely and magically transported thousands of miles away. Magic is difficult.
Quick! It must be the conspiracy! Start demanding proof that anyone has circumnavigated the globe pole to pole! If they have, start insisting they're part of a NASA conspiracy!