There was some chatter here awhile ago about DNS/DNF and I forget the split but DNS was the much higher number. I think underestimating the training is part of it (there was just someone over on Reddit asking if they could do Dopey in 2027 after starting a couch to 5k plan three *weeks* ago

) but you also have transportation issues, budget issues, injury, emergencies, etc. There are a lot of reasons someone would have to bail and I think this being a destination race as opposed to your local half or full impacts things.
The person posting about requiring proof of another marathon to run this one was ridiculous and they got lit up over it. I don’t even know if that thread is still there.