I'm not going to defend flat earthers but I think it's important to understand where they are coming from:
Part of their philosophy (maybe not for all but still) is to put earth back into the center where it always was. In other words: they don't want to accept that earth is just one of many planets. Earth is the world and everything else are just lights on the sky. You can't deny that Mars is a round celestial body but you can deny earth is. So earth is still special and so am I and so are you.
It's complicated. They colonised an entire continent they call "Australia" a little over 200 years ago by genociding the natives. They let that stew in relative isolation and develop its own unique way of talking, and now when an Australian's native accent is attempted by those not born here it's extremely difficult for them due to said relative isolation.
Now, this sounds like I'm describing a real country, but it's a conspiracy somehow.
EDIT: Definitely downvoted for the genocide comment. Coloniser mad lol.
I think it's a great idea to rally up a lot of people and demand that the government prooves that Australia exists with a paid, all inclusive, week long trip to one of Australia's finest resorts.