Can someone explain this physics concept?

Think you've got a basic missunderstanding: It does not matter how fast you throw the thing horizontally it stays aloft for the same time (It simply falls under the acceleration due to gravity in the normal way, it hits the ground further away if thrown faster, but it was going faster so took the same time to get there). This is assuming a horizontal surface, if the curvature of the earth is taken into account then you have a point.