Being a clan leader is like attempting to herd a group of particularly feral, vicious cats by use of a remotely controlled roomba. Recruiting, retention, drama, coordination, and just getting people to all be online to do stuff is a nightmare. I was an officer in one and later got promoted to leader in a somewhat-related one, and while I don't regret doing it (my core group of Internet friends are almost all from that period), I can't imagine ever doing something like that again.
Given my 'druthers, I wouldn't be in one at all because I do fine hanging out with my close friends and in game-related chats for 'pick up' groups, but being a member is way preferable. You have to be built the right way to lead, as Zyni said. Personally I can't administrate more than a dozen people without losing my mind, though I'm usually fine moderating and get roped into that more often than I'd strictly like to.