The horizon is a circle centered on the observer. By definition, a circle is a figure in 2 dimensions, so inscribed in a plane.
The fact that the horizon is a straight line doesn't disprove Round Earth. On Round Earth the horizon is always a straight line.
You can take as many pictures of the horizon as you want, it doesn't help Flat Earth.
Oh, yes, a "straight line" does in-fact dis-prove Earth is a Ball.
No, it doesn't!
Suppose I'm on the Globe earth looking out over a calm sea with eye-level 2 m above sea-level.
Then, according to
Metabunk's Earth's Curve Horizon, Bulge, Drop, and Hidden Calculator the horizon is said to be 5.05 km away.
The same app claims that the horizon is 0.045° below eye-level and that horizon would be 4 m below my eye-level.
So I would be looking at the edge of a 5.05 km radius circle from a point 4 m above its centre. A circle look at so close to edge on looks so close to a straight line that one could not tell them apart.
I'll do the sums if you insist.
Even you must agree that the horizon line would look so straight that even with a straight-edge you could detect no curve.
This following photo was taken from about that height above a fairly calm sea on a camera with a standard 50 mm focal length (35 mm equiv) lens:
Scarborough Beacon 50 mm lens - higher res, cropped top and bottom. Looks perfectly flat and quite sharp to me! Just as expected on a huge Globe.
So when flat-earthers say that the horizon looks perfectly flat and sharp they are quite correct.
Is there anything else you like me to agree to?
You just can't accept the fact that simply geometry proves you wrong. It's that simple. You know I am right, you're just not going to openly say so because of your beloved fact-less theory.
No, I cannot agree to that one! Simply geometry does not prove me wrong. If you disagree show me your simple geometric proof.
And please desist in you inane and dishonest claims like, "You know I am right, you're just not going to openly say so because of your beloved fact-less theory."
Don't you dare claim that you know how I think!