The chances of..

Chance of NASAs photograph. evidence being faked : 50% , 1/2
Chance of Space-Travel being faked. 50%, 1/2
Chance of NASA just doing everything for money: 50% , 1/2

NASA: 1/2 x 1/2 x 1/2 = 1/8 = 12,5 %

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Chance of FE Evidence being false : 75% , 3/4
Chance of FE Forum being a giantic joke by daniel : 50% , 1/2
Chance that half of fe forum members never went to school : 75% , 3/4

FET: 3/4 x 1/2 x 3/4 = 1/2 = 50%


NASA 12,5 chance being a hoax...
FET 50% chance being a hoax...

i'll stick with nasa...

Chance of NASAs photograph. evidence being faked : 50% , 1/2

This is where I stopped reading.  You are confusing a binary state (photos faked or aren't faked) as a 50/50 chance.  Allow these examples to show you your error.

Chance of you being human: 50% , 1/2

Chance of Obama winning the next U.S. Presidential Election: 50% , 1/2

Chance of Astrology being real: 50% , 1/2

The options aren't independent variables.

If the earth is flat then all of the  NASA pictures are 100% fake.   If the earth is round,  then there is still a non-zero probability that NASA pictures are fake.
If any of the NASA pictures are real then there is certainty that the Earth is round. 

So if you wish to prove the earth is flat, you have to prove that ALL NASA pictures of earth from space are faked.
If you wish to prove the earth is round,  you only have to prove ONE of the NASA pictures of earth from space is real.

Even if you can prove all NASA pictures are fake,  that still doesn't prove the earth is flat.