The issue is not the lack of speakers but the lack of organizers' understanding of targeting. If you like everyone else is doing an event for bitcoiners, 300eur and more for entry, then you neglect the millions of potential visitors that are complete noobs and would like to learn but probably for 30eur or less in entry fee. Then, you don't need to invite top notch developers or business owners, but rather bitcoin savvy teachers. Just an example. Another potential audience is legacy finance experts. Again, different audience, different speakers.