“Dispute the credit card transactions.”
that’s what i’d do ... if tens of thousands of peopled did that, the organizers would have a hard time responding in a timely manner to all of the disputes and would automatically lose the ones they couldn’t respond to ...
They will simply lose. It is one thing to say that you don’t get a refund if you don’t go for whatever reasons, but to say you don’t get a refund if the organization cancels, is a very different thing entirely. Besides, back to the credit cards, the processing companies will cancel them if they get significate disputes, which this will lead to. That will be expensive.