It never crosses my mind to compare prices and value on what is brought, and make sure that everything is 'even', I'm too busy fellowshipping with my friends and having fun. Should we start doing that with food we bring, too?? Geez, I brought expensive brie cheese and Sally only brought potato chips. I just don't see how anyone is supposed to enjoy themselves doing that kind of stuff. As far as you not getting any of the expensive drink you brought, if you grabbed one right away, you wouldn't have that problem I think.
But maybe I brought Mike's because that's what I want to drink for the night. Say, I don't like beer. Everyone else has brought X brand of beer and then they see my Mike's. One person decides they'd like a change of taste and decide to dip into the Mike's, then the next person does and so on. Before we know it, all the Mike's is gone and I've only had one and I planned to drink all 6. That's my prerogative.
We were in FL a couple years ago for a family wedding combined with a family reunion. MIL rented a fab house right on the beach and it slept about 15. It was the homebase for everyone, including the people who stayed in other accommodations.
DH and I bought a bottle of vodka (a 26'er) and a big bottle of strawberry daiquiri mix. While we didn't buy it for us entirely, we didn't anticipate that SIL would make virgin daiquiries for the 20 some odd kids. Dh and I didn't get one and it cost us about $40. SIL was the 'bartender' and made some fab drinks for everyone and when it came to our turn, all the mix and vodka was gone. We bought the mix and vodka together for the adults and SIL took it upon herself to include the children in what we considered to be an adult activity. I wouldn't presume to make drinks for everyone with someone else's mix and booze.
I'm not saying your way is wrong. It's just not done in my social groups. BYOB means 'bring your own booze'. That doesn't mean it's a free for all, especially when the person bringing it doesn't get any.