That sharp horizon on the image I posted could be indicative of what an infinite (or very very large) flat Earth looks like. All the image would show is there is no ice wall (or that the ice wall is beyond our sight and/or too small in height to make out) We aren't looking at the Earth from a birds eye view here, we are looking along the horizontal axis.
If the earth were infinite there couldn't be any edge to see.
"We aren't looking at the Earth from a birds-eye view here" but if:
the same curve is seen in all directions and
from such balloon flights in many locations on earth
we can deduce far more about the likely shape of the earth.
And if you look at an image (out of context) and you see a few degrees of curvature, do you automatically assume it MUST be spherical shaped?
No, I take that as evidence that the earth is 'not flat'. That is different.
But when such images all have a curve, no matter where on earth they are taken, it provides evidence that the earth could be a sphere-like object.
That is stupid
Sure and look who suggested it!