I have been first volunteer many times and was not part of the eventual VDB.
If they need two and there is a couple travelling together you can bet that the GA will take them over you as it mean only one PNR rerouting.
Even if they only need one they might take the easier to reroute, no need to pull bags and/or other reasons into consideration. Being #1 on the VDB list does not guarantee that you will be the first to get VDB.