The Earth is flat. The Earth is round. Both of these are true. Expand your mind to find out how. Flat earthers don't understand that the most convincing arguments they present don't actually point towards the Earth being flat. A lack of visible curvature and direct airplane flight paths, if we follow the scientific method, do not necessarily land us on the conclusion that the Earth isn't spherical. There is something stranger that precedes the flatness theory. In truth, the strongest arguments for flat Earth would point toward a much more stranger idea - not that the Earth is flat but rather that the Earth is much, much larger than we currently know. For the sake of expanding one's imagination, I'd say it's worth pursuing this particular train of thought. Who knows what kind of strange new ideas you might fall into. :)