The party was at the Louis Vuitton flagship store.
Kanye West has a relationship with LV.
I don't think it's odd for his birthday party to be there, as it's completely a marketing ploy for both Kanye and LV. There are a lot of parties at fashion stores. Barneys throws one every season for fashion week. Stores, especially flagships, tend to be in a great location, be large enough to host, and already have the security infrastructure to host larger parties.
As for stealing, I guess it would be tempting. I personally have never thought about it, even though I guess it would be easy to do so because although there are cameras and security walking around, you cannot focus on all guests at once. Stores do not lock down all of their merchandise when they throw these parties. Certain areas tend to be blocked off, and jewelry is removed or locked up more carefully, but there is too much to move. I think the reason stores are not super cautious is because the fashion/entertainment world is very store and everyone knows everyone.
I think it's weird they might make Pharrell reimburse the $30,000....
I almost went to Kayne West's party.