My understanding is that FOSDEM is run by volunteers on a shoestring budget mainly thanks to the support of the ULB (a university). They don't have security, they don't have badges or registrations, you can just walk in and out as you please. I have my doubts this is going to last if people start to deliberately try to take a fat dump on it to elevate their own ego.
FOSDEM organiser here. The shoestring budget is accurate, as is the badges or registrations thing. The security thing is not. We do have proper security. Organising an 8k people conference without would be unsafe and illegal.
