You think we’d see a curve on the surface over three miles and beyond it?
Depends on your altitude.
From a low enough view point, we do see it easily to three miles, but not beyond it.
i.e. a horizon forms.
Because that is a curved surface works.
Conversely a flat surface you don't have the horizon and can see beyond those three miles.
If you want to say we should see it some other magical way, then stop beating around the bush and clearly and directly explain just what you are expecting to see.
When doing so, make sure you justify it from the RE model.
The surface of Earth is just the same as any other surface, and can be measured for its shape.
And just like all measurements, there will be some level of unceratinty.
But with accurate enough instruments over a long enough distance it is clear that Earth is round.
Your lies wont change that.
When we view the horizon three miles away from several points parallel to it, all three miles away, what do you think you’d see of it?
Or view it moving parallel to it three miles away?
Pretty much the exact same view we have.
And we would expect this roughly the same view regardless of if Earth was round or flat.
Just what do you think you would see?
If it WAS curved over the surface, we’d see a slight curve downward from the mid point of our position.
No, we wouldn't.
The surface has the same angle of dip in all directions. So no, we do not see a curve downwards.
The only way to see that is if you go high enough above it and look down, so that way a curve towards a point below you, in the same plane as the horizon, appears as a downwards curve from your view.
But for a view close to the surface, you are so close to the centre point of that circle (compared to its size) that you will not see that.
The circle you are trying to see is obstructed by the horizon.
Because it could NOT be flat, nor LOOK flat. A curve must always exist and be seen on a curved surface.
A circle is flat.
And you have been provided with plenty of examples of a small enough region of a large enough curve being indistinguishable from a straight line.
When you look over your floor outward, it appears to be rising upward. How do you know it is NOT rising?
By understanding basic geometry. Something you are trying hard to pretend you have no idea what it is.
One way is to use a theodolite and measure the angle of dip to various points on the surface.
Another simple way (which only checks for level, not flat) is to use a level of some sort.
You look at the floor across from it, moving parallel to it.
No, you don't.
Because that doesn't work at all.
That relies upon you having a reference you can compare it to.
Imagine you are on a ramp, looking at something built on that ramp.
Looking at it, as you move up and down the ramp, it looks the same.
That doesn't mean it is flat.
Otherwise, the best you get is a view is when you are very far away from it, so it is akin to an orthographic projection.
Doing that for Earth and you need to be in space.
But if you are just interested in flat, rather than level, you get as close as possible to the surface and look along it (outwards as you would say). If you can't see the entire surface, it is curved.