Look, we all get into weird stuff when we are young and impressionable. For some people, it's enjoying the questionable music of boybands, for others, it's eating Tide Pods.
And for some (who are old enough to know better), it's getting sucked in by conspiracy theories, such as Earth isn't round and NASA – and, crucially, pretty much the whole of the planet – is hiding this fact for gains that are as yet unclear.
As with planking and the solo career of Liam Payne, people do grow out of their beliefs and are comfortable saying so. In a thread on Reddit, former flat-Earthers and the people that know them have been letting others know what it was that finally made them realize they were standing on a globe, not a pancake.
For some, it was seeing it for themselves.
"I have an acquaintance I met in the Navy, who joined specifically so he could see that the Earth was flat while at sea," user TrungusMcTungus wrote of their extremely committed compadre.
"Every day he would chart the ships location, speed, heading, etc, a few times a day so he could make a map of their path. Ultimately he realized that the path the ship was taking would be impossible if the Earth was flat, based on the distance they were traveling vs their speed."
The man apparently became suspicious that the Earth was actually round, but before he could take steps taken by scientists centuries ago and figure it out for himself, his Leading Petty Officer "pointed out the curvature by giving him binoculars and explaining that if the Earth was flat, he should be able to see the land they were making for," the Redditor wrote. "He couldn't see anything off the horizon. After that, he was convinced."
Unfortunately, as you generally sign up for a minimal four-year contract, he was now stuck in the Navy having proved to himself the exact opposite of what he'd set out to.
Another, who couldn't even be bothered to join the Navy to prove their belief, made the same discovery by watching a video on the Internet (which is often how people get in this mess in the first place).
"I saw a video of an experiment where one group flew a helicopter far out over the ocean and another group watched it with a powerful telescope as it slowly lowered to the horizon," they wrote. "It disappeared behind the horizon while the helicopter was still a considerable distance from the ground. That ended that phase for me for good."
The video in question, if you'd like to save yourself 4 years in the Navy.
For most in the thread, their belief got stripped away when the theory didn't fit with experiences they'd had themselves or other facts that they know to be true about the world.
"As someone who entertained but never genuinely believed the idea and went pretty deep down the rabbit hole, it was distance/time," one user explained of what made them see the light. "On a flat-Earth map, circling the North Pole should be an extremely short trip while circling the South Pole would be the longest route on the planet. The further south you get, the further apart things should be and the longer trips would take. The flat-Earth map really falls apart there."
One user told the story of how he and his mother went down the flat-Earth rabbit hole, before ultimately realizing that a lot of it made no sense, particularly the claim the Moon produces its own light (why are there crater shadows?) and the fact it's quite clearly documented that different constellations are visible from the Northern and Southern Hemispheres.
"By asking these questions, my mom [who taught science at elementary level] eventually realized that the flat earth "theory" made no sense," they wrote. "My mindset when approaching the theory was 'We can make observations about how things behave, and come up with different explanations for what causes them. So let's compare the flat and globe earth theories and see which holds up better.' We both came to the conclusion that the flat-Earth doesn't adequately explain many of the things we observe on earth."
Which is, in a nutshell, how science works.