what proof is there for a flat earth?

They took pictures from space, the earth is round

I've been studying flat earthers for a few years and what I've found is somewhat startling. These are mostly grown adults with childlike mentalities. They only want to hear what agrees with what they already believe. If you try and educate them at all, they will accuse you of being a shill, a government stooge and that leaves them free to ignore whatever you say.  A standard flat earth proof usually involves a question with a fundamental flaw. They take that question to some illogical absurd point and then say "See? See? What we are told could not be true."  The fact is most of them don't have the mental capacity to understand what we are taught so these questions they come up with seem perfectly valid to them. They have chosen to imagine that NASA is nothing but a bunch of CGI artists and anything we see from NASA can't be believed. Flat earthers can not understand anything that is abstract. For instance, to a flat earther, "down" can only be one direction. So the idea that someone can be on another part of the globe and experience down as a different direction from him - well that creates a logical impossibility in his brain. They often confuse a word with the thing it represents. I remember one notable flat earthers who disbelieves in gravity went to great lengths to re-frame a "pull" force as a push from the back side. When he was done he thought he had discovered something no other physicist had ever thought of before and sincerely believed he had proven science wrong. Now, gravity exists no matter what name you choose to apply to it. And the effect of gravity exists regardless of what words you use to interpret its effects. 

The upshot of all this is in 4 years, I've not seen one stick of evidence fall in their favor. Once in 10 years there might be a weird atmospheric effect that makes something far away appear on the horizon but these are not the norm, they are the rare exception. On the other hand, if you ask a flat earther, the only evidence is in their favor and they haven't seen any proof come from us at all; never mind that we can provide thousands of pictures of the spherical earth from space and they can't seem to provide one of a flat earth...  not one...  Ever.

These are a people in deep denial who believe in a world wide conspiracy to hide the truth yada yada yada...  Oh yeah, I forgot to mention, another one of their defects is that they are terribly BAD at estimating the likelihood of one scenario over another. That's why a conspiracy where all of the news media, both print and TV is working for all of the worlds government seems to be the most likely answer to them. Best thing to do is avoid them. It has all the marking of being a cult.

Ignorance is the only proof for a flat earth

There is NONE--that's why many serious "Flat Earthers" like it so much---It relieves them of the obligation to have to study things like gravity, orbits, astronomy, etc.---You get the idea----A "lazy mans science".

Proofs are valid in math

Welcome to the 21st century.

Flat earth people don't have any evidence. But they don't need any. Evidence is not required for their beliefs. All evidence against a flat earth is ignored. They don't believe the laws of physics either. Not do they believe in moon landings, space probes, satellites, or high altitude planes or balloons. 

There is no such thing as a flat earth "theory".  The earth is not flat.  That is a fantasy.  There can be no SCIENTIFIC evidence for a fantasy.  

Since the earth IS round there CANNOT be any evidence that it is NOT round.

there is zero proof, zero evidence for a flat earth.

Uh... uh.. uh.. wELL, IT's aLL mEdiA pRoPagAndA. eArTh iS fLaT bEcaUse wE sAy so.