Even if they paid “wholesale” it’s still remarkably expensive.
In the grand scheme of things, it's not really that expensive. That's not what they eat and drink all of the time. Once a year, I dine fine. Generally, I pick a restaurant that I've slaved in, or know the owner. I still spend all of my birthday money for one meal. Once a year.
The last time I deployed, I got a comp meal for me and a friend, and the owner (to my surprise) comped the matching wines as well. I got a rough idea of the total cost from the M'd and tipped accordingly. The meal was free. The matched wines were free. I tipped over $70 for me and the other TSgt.
The good stuff is pricy, but it's not for every day.