Actually a flat earth is much more simple.
The complications associated with the current ball earth understanding are numerous.
Not when it comes to (1) the assumption of world-wide conspiracy vs. no world-wide conspiracy and (2) the scientific consequences.
*A round Earth is a natural consequence of the law of gravity. I do not know of any force which would naturally result in a flat Earth. An explanation would also be needed to explain why the Earth is flat when the Moon and other astronomical bodies are round. What makes the Earth unique in terms of the forces affecting it?
*The round Earth model requires fewer forces than a flat Earth. Gravity not only explains the force holding us to the ground and why the Earth is round, but it also explains the orbits of the Sun, Moon and planets, whereas it cannot be invoked in a flat Earth cosmology. A different force than gravity has to be used to explain why we are held to the Earth (because, if gravity was truly responsible, it would have crushed the Earth into a spherical shape). A different force than gravity also has to be invoked to explain the motion of the Sun, Moon and planets (as they do not follow orbits that are consistent with a gravity-centrifugal force model). Somehow, they are levitating above the flat Earth. The round Earth model is more parsimonious in this respect.
*I've seen "gravity" on a flat Earth explained as the Earth accelerating upwards at a force of 1 G. This would require yet another force to explain this movement. If this was indeed the case, then the Earth would be travelling faster and faster all the time. Eventually, even the dust particles in space would be moving quickly enough relative to the Earth's movement to cause severe damage when they impact it.
*The round Earth model can explain plate tectonics, volcanic eruptions and the Earth's internal heat as a consequence of the Earth's initial formation from gravity. Where does the internal heat come from on a flat Earth? Likewise, the residual heat combined with Earth's rotation serves as an explanation for the Earth's magnetic field (which arises as a natural consequence of flowing liquid metal). This explanation would be unavailable on a flat, non-rotating Earth.
*The atmosphere is held on by gravity on a round Earth. Something else has to be holding it to a flat Earth. If it is somehow held there by a physical barrier, it would have to be composed of a substance with a significantly higher strength-to-weight ratio than any material we know of, as it would have to be tens of thousands of miles across. Also, how would meteors ever crash to the surface of the Earth if there is a physical barrier in the way? Or are meteors another part of the conspiracy? The gravity-held atmosphere is the simpler explanation.
*As I pointed out in an earlier post, the laws of aerodynamics would have to be different for travel times by plane on a flat Earth to be workable.
*Gravity-powered nuclear fusion explains how the Sun shines very well in a round Earth model (including its composition and spectrum), but cannot be invoked when the Sun is assumed to be smaller than the Earth (which is the case in most flat Earth models I've heard of). Guess the Sun's spectrum must also be a part of the conspiracy...
*Between two models capable of explaining a phenomenon, the one which doesn't require some kind of global suppression of knowledge for hundreds or thousands of years without slip-ups and a questionable goal is strongly favored by Occam's Razor (especially if the best evidence for the conspiracy one can drum up is "if the Earth is flat, then there
must be a conspiracy!").
*If the Earth really was flat, then how did the whole round-Earth thing start in the first place? Some group would have to have started it, but for what possible reason justifying spending so many international financial and political resources throughout expansive eras of history on it? It would be massively easier to just let the flat Earth thing keep going if that's how reality really worked.
It's possible. I have seen little circumstantial evidence that those places don't exist. On the other hand, I've seen much circumstantial evidence that the earth may be flat.
I think I've seen you mention one thing (seeing something that should be beyond the horizon, was it?) What are some others you know of?