I would imagine, as with many non Airsoft events, people go for the event itself, much like NAF. It's not just the airsoft, it's the size of it, the social aspect etc.
And then, taking music festivals in as an example, some can be utter shit shows but still make money every year.
There's one metal festival I won't go to for various reasons, but the final deciding factor for me is that the regular crowd consists of utter tossers. And I'm not the only one that feels that way.
But it's a big event, makes loads of cash, despite even the regulars thinking the organisers are assholes and complaining vociferously about the event on social media.
But they all go again next year.
Airsoft events as big as NAF and AI500 aren't really that widespread, as they're a ball ache to put on, so for those that want a BIG experience they don't have that much choice.
None of the above excuses the poor organisation I've been hearing about from AI500 AGAIN, just musing on why people keep going back.