What about a plane suggests that it needs an edge?
Are you suggesting that the flat earth is infinite?
I'm suggesting that there is no mathematical reason for a plane to have an edge.
That being said, if physical space is theorized as infinite in nature... why does that sentiment not extend to our physical planet?
If the Earth is flat, and surrounded by an innavigable expanse of ice, than who's to say that there is an edge?
What about an expanse of ice is not navigable in an era of long distance air travel? Even if there is a ring of ice around this planet, then why has no one flown out over the ice to see what lies further out? There are lots of daring adventurous types on this planet. Why has no one ever risen to this simple challenge?
And of course, the bipolar flat earth map just raises the same question: what lies beyond the edge of the map? Why has no one ever flown an airplane beyond the edge of the map and reported back what they found, whether that was more water, or distant lands, or some kind of dome like structure?
Or is it simply possible that if you keep going in the same direction, you always end up back where you started as is found to be the case on this round earth? This is true even when circumnavigating north and south:
https://en.wikipedia.org/wiki/Transglobe_Expedition