You don't understand (I'm not surprised). I'd like to see you state this:
It's magical because you provide no explanation regarding the thickness.
It's just the usual vague guff that comes from flat earthers.
in the form of this:
Appeal to Ignorance:
There is no evidence against p. Therefore, p.
There is no evidence for p. Therefore, not-p.
There's no evidence for the earth to have a known thickness. Therefore the earth has an unknown thickness.
What this amounts to is "we haven't really tried".
The bluntest appeal to ignorance possible I imagine.
Damn, I give up. You can't argue with someone who doesn't have a clue of what he's talking about.

Here are some questions for you:
Exactly how many atoms are there in the spherical earth?
What was the exact date of the Big Bang based on our modern calendar?
If you can't answer these questions accurately, IS THAT AN APPEAL TO IGNORANCE?