A rebuttal.

Where's the curve?

Right here.

That is a scale image of the earth's curvature. It is drawn at a scale of one pixel per eight inches. It shows a two mile section of the curve. There are 126,720 inches in two miles, so divided by eight we get 15,840 pixels wide. The earth curves 8 inches per mile. So the scaled image of the curve has its center 1 pixel above either end.

Here is the kicker. The typical human's horizontal field of view is about 135 degrees. The distance to the horizon if your eyes are 6 feet above sea level is about 3 miles. That means you would see the horizon as an arc about 7 miles long. The drop from the center of that arc to each end would be about 8.17 feet.

So I scaled that down to an image where 1 pixel equals 3 feet. That gives me a curve 12,441 pixels wide with the center of the curve being 3 pixels higher than the ends. This is actually more curve that the earth actually has because I can't draw 8.17 feet as that would be 2.7 pixels, so I rounded up to 9 feet/3 pixels.

This is what that looks like.

That's why you can't see the curve.