Firstly, your diagram was from the view point of someone in orbit over 1000km above the earth's surface, way beyond what you claim is the limit of the 'dome' so hardly a reasonable comparison. The earth's radius is around 6371km and any comparisons need to take that into account. If you want to mock the globe model then you need to deal with the actual globe model, not a strawman model of your own making.
Secondly, your diagram ignores the effect of perspective when dealing with large distances. In the flat earth model the horizon is effectively at infinity where everything converges to the vanishing point. In your diagram you are looking down at the ground, not looking out at the horizon where the sky and the ground/water meet. It is completely wrong.
So I did the math for the three elevations in the video with the water level in post #479
- At sea level, with an elevation of 1.8m the horizon is at 4.8km and the drop from eye level to the horizon is 0.043°
- From Malibu, with an elevation of 365.76m the horizon is at 68.5km and the drop from eye level to the horizon is 0.615°
- From Mt Wilson, with an elevation of 1708.6m the horizon is at 147.6km and the drop from eye level is 1.327°
- From the ISS, with an elevation of 400km, the horizon is at 2294km and the drop from eye level is 19.793°
Calculations are basic trigonometry using the values above. Angle of drop from eye level is the same as the angle between the two radii, since eye level is perpendicular to the viewpoint radius.