It is true that personal gain within clan is not selfless but what I mean is if a person is to gain more than you would personally from the same item and their input is just as much it is I believe a fair thought to "consider" the other above yourself when considering (if use dkp) before bidding if the gain is far greater on their behalf to a much smaller one to yourself.The price of teamwork is exactly the difference between what you can achieve with and without it.
All that is valuable is not golden,
you can't put a price on teamwork sure there are merchants in game but these aren't team players more so self thoughtful to personal gain.
A true clannie believes in sacrifice for the benefit of clan and its members and in return the clan and its members return the same thoughtfulness
Btw I'll just go and say that there is no selfless sacrifice in clans for any player that really is socially aware. If members aren't benefitting more than they could independently then it's a good idea to leave the clan. Personal gain through cooperation should not be taboo and is a cornerstone of how the actual world works.
But yes teamwork, cooperation, willingness to swap builds if required, playing roles within strategy even if it is not the role within you would most ideally like, things like these I'm talking about.