“Let’s call it 666curvemath for short.”
Let’s call what you’re doing what it is, ignorance. Your video conflates an optical vanishing point with the true horizon. The optical vanishing point is a function of the limitation of the human eye. The bottoms of objects don’t disappear to view, the whole object becomes too small to be distinguished.
A landmass like an island doesn’t become too small. And you see its heights at a distance but you don’t see its coastline.
At three miles, there is a six foot "drop" over the curvature of the earth. At ten miles, it is a 66.6 foot drop! You simply would not be able to see the buoy in this video:
SHIPS (NOT) DISAPPEARING OVER THE HORIZON
https://www.youtube.com/watch?v=kSVrfw3znds
THE MATH BEHIND THE CURVATURE OF THE EARTH
Statute Miles Away Math = Drop
1........ 1 x 1 x 8 = 8 Inches
2........ 2 x 2 x 8 = 32 Inches
3........ 3 x 3 x 8 / 12 = 6 Feet
4.........4 x 4 x 8 / 12 = 10.6 Feet
5.........5 x 5 x 8 / 12 = 16.6 Feet
6.........6 x 6 x 8 / 12 = 24 Feet
7.........7 x 7 x 8 / 12 = 32.6 Feet
8.........8 x 8 x 8 / 12 = 42.6 Feet
9.........9 x 9 x 8 / 12 = 54 Feet
10........10 x 10 x 8 / 12 = 66.6 Feet
20........20 x 20 x 8 / 12 = 266.6 Feet
30........30 x 30 x 8 / 12 = 600 Feet
40........40 x 40 x 8 / 12 = 1,066.6 Feet
50........50 x 50 x 8 / 12 = 1,666.6 Feet
60........60 x 60 x 8 / 12 = 2,400 Feet
70........70 x 70 x 8 / 12 = 3,266.6 Feet
80........80 x 80 x 8 / 12 = 4,266.6 Feet
90........90 x 90 x 8 / 12 = 5,400 Feet
100.......100 x 100 x 8 / 12 = 6,666.6 Feet
120.......120 x 120 x 8 / 12 = 9,600 Feet
Again, note the times "666" happens to come up here in the curve math. "666" comes up in all globemath.
I'll address the perspective/optical illusion/mirage issue next if I can find the link.