I personally stay away from large conventions simply because between the cost of admission (I'm not paying $40 to look at action figures) Cost of parking, gas, I've already spent $200 before I even stepped foot inside and It's way overcrowded, I get dizzy with all the people walking by me cause that's all I see, is people, It's hard to get at the dealer's table with all the clowns who have their notebooks spread out all over the boxes while they wear their backpacks, I see that I usually just skip that dealer or come back when it's more accessible.
I think promoters want to try and cast as big of net as possible when doing a convention cause not everyone who goes, collects comics so they can get the admission attendance up, so they'll make more money and tell dealers "Hey! Our attendance last year was 125K! That'll be $5000 a table please!"
I love the small local shows, I have a monthly ones 10 mins from my house I go to all the time. Talking to dealers at these small shows it's more about making small sales, people go for the cheap books. For a $35 table they can walk out with 1-2K in their pockets for doing a 5 hour one day show. Show is all 95% comics.
Slabs are for the internet.
If dealers are struggling with Wizard shows, then just don't do them anymore, seems like they are becoming more of a liability than an asset.