Why do you think the earth is flat?

It baffles me as to how a person, sane or insane, can actually think the earth is flat.

You do know that since the time of the ancient greeks, we've known for a fact the earth is round right?

Did you know since the time of ancient hominids, the Earth was known to be flat?

Did you know since the time of ancient hominids, the Earth was known to be flat?

that was because that idea was based on extremely limited observation. The ground must be flat, therefore the earth must be flat.
however, shadows have a slight curvature to them. the ancient greeks used this to figure out the earth is round and estimated the circumfrence of the earth to within about 10% accuracy