I believe that meals are at-cost, so TDIClub makes $0 on them. The only fee going toward TDIClub is the registration fee, and a significant portion of that is allocated toward the t-shirt, name tag/lanyard, office supplies, etc., required to conduct the event. TDIClub makes little on each registration. If the hotel rooms were not sufficiently booked, then TDIClub (actually, the planner that signed the contract, but I'm assuming that TDIClub would cover the cost) would be liable for fees/penalties incurred for failing to meet the room block quota. I don't have all of the numbers, but I've seen room attrition cause an otherwise profitable event to go significantly in debt (by thousands of dollars, and in one case I've seen, tens of thousands).
Do any of you remember the reports on TV in the recent past, how Wells Fargo and other banks and large institutions that have been recently bailed out by the federal government were continuing to spend enormous amounts of money by having parties and conferences at hotels? I don't know the details in each one of them, but for some of them, the events had already been scheduled, and it would have cost the event managers *more* money to cancel the event than it cost to conduct it.
The only way for your "they're paying the registration fee, get over it" argument to work is if the event 1) raised the registration fee for every attendee, significantly, so that the club could cover the penalties imposed by the hotel due to failing to meet room quotas, or 2) charged a penalty to those registrants which did not reserve a room in the room block, or who are sleeping more than X people in one room in the room block, where X is a formula providing the estimated loss incurred by each N registrants for not reserving rooms in the manner targeted by the event planners.