I suppose you can believe whatever makes you happy but your theory requires altering the laws of physics to:
A) Add some strangely unmeasured refraction to light
B) Discard the force of gravity entirely
https://www.lhup.edu/~dsimanek/flat/flateart.htm
It appears that the flat-earther's figures are based on sun elevation data at just two particular latitudes, perhaps even Eratosthenes' values. flat earthers may have picked these out of some book, and when the calculation was finished, they looked no further. For if they had done the calculation with a variety of latitudes, including large latitude differences, conflicting results would have been obtained.
For two towns having latitudes within about 30° of each other, reasonably consistent results are obtained. But when larger baselines are used, the triangulation would give a much smaller distance to the sun. For a 70° latitude difference the distance to the sun comes out less than half that for a 10° difference.
How about airplanes and earth satellites in orbit around a flat earth. And what about airliners going around the earth? What about earth satellites? They are merely traveling in loop orbits. What makes them do this? Flat-earthers do not say. Flat-earthers shun any form of gravitational force. They consider gravity to be a mystical or occult idea. Things fall, they say, simply because they are heavy—no other explanation is needed. What about the moon flights and the pictures from space showing a round planet. It's must all be a hoax, an elaborate movie production.