To put on a gun show, an organizer first has to find and rent a large facility which doesn't come cheaply. Then they have to rent tables and chairs if those are not included in the facility rental, and either set those up themselves or pay someone to do so, then take them down and make sure the facility is cleaned. Or they have to buy enough tables and chairs and then have those transported to the various locales, often hundreds of miles apart. They have to pay for 24 hour security typically from a Friday through Sunday. They have to buy insurance and advertising, then there is all the time spent in administering all of the aforementioned.
If they don't advertise enough and public turnout is poor then fewer vendors will rent tables for their next show. It it's administered poorly then same thing, fewer vendors rent tables for the next one. Fewer tables and/or fewer vendors means the public feels cheated so they don't come back.
Their sole sources of income to pay for all of that are table rentals and entry fees. Income from table rentals is maxed out at the number of tables available so their income is mostly determined by how many people show up.
It's not a cheap undertaking but a well run show does generate a good income. Our gun club used to put on one show each year in a large facility - the Western Idaho Fairgrounds. It was a major project and cost several thousand dollars to put on but it was well run and had a good reputation among vendors and the public so turnout was generally very good.
Gunnery, gunnery, gunnery. Hit the target, all else is twaddle!
