Life would not be sustainable because:
1. Water would not be able to stay since it is flat, and it would just float off into space
2.Since the earth is flat, the core would not exist, meaning that earth would have no heat from the core, and nothing would be held together since the core is like a magnet
3. Since the earth is flat, earthquakes would destroy the earth\
And that is why the earth is NOT flat and why life would not be sustainable on earth if it was flat
