This isn’t exactly a ‘science debate’ but I’ve met several people that still think the ‘Great Wall is the only man made object visible from orbit.’ I read somewhere that may come from a dream some Chinese king had like 1000 years ago.
Almost crazier than flat-Earth in terms of being easily disprovable just by thinking about it for 20 seconds, but people have stated that to me as a fact and were kind of incensed when I explain it’s obvious nonsense.