@thomasfuchs Yeah, that is the worst!
I've been involved in events where there were just a handful of speakers and only about 50-100 attendees, and no one had to pay anything and all accommodation and travel costs for speakers were covered by sponsorships.
And I'm certain that it can be scaled up. And I'm not saying conference should be free, but I doubt that 500 or even 1k€ tickets are justifiable.