-Why would organizations like SpaceX and Nasa want to perpetuate the idea that the Earth is round? What would they gain?
They don't.
https://wiki.tfes.org/The_ConspiracyShouldn't all planets be the same shape?
The Earth is not a planet. But no, the argument of "All these things are of one shape, so why should another thing be different?" is not a strong one by itself.
What happens if you keep going forward for a long time? Wouldn't you fall off the planet since the Earth is disk?
Thanks to the extremely inhospitable conditions beyond the Ice Wall, you'd die much sooner than it would take you to establish whether or not there even is an edge.
What about all the times that people have kept going in the same direction for a long time and have ended up where they started.
Regardless of the shape of the Earth, they haven't kept going in the
same direction. On a Round Earth, they'd have to follow the Earth's curvature, otherwise they'd simply waltz off into space. Identically, on a Flat Earth, circumnavigation is achieved by travelling in a circular pattern.
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