It always sucks when you see a valuable member contributing great content causing problems on your forum. Years of constant praise and allocates can go to a members head. They loose their head over their superstar status on your forum. Suddenly one of your best contributors has become your worst nightmare. How are you handing these situations as an admin? Are you doing your best to retain high profile members with out of control egos? Are you doing anything to manage their egos effectively or do you throw the ban axe at them when they become too much of a problem for your members and staff?
I'm not sure how valuable any member is if they are causing problems for the other members. What are they doing? Are they violating your rules or just a little too full of themselves and it's rubbing the other members the wrong way? How do you handle a member with a lower post count who does what this one is doing?
The only circumstances when I've seen this happen is where a long standing member has been given some degree of power such as moderating abilities.
I usually contact the member to see if they can be reasoned with. I explain how the behavior is impacting other members. I try to see if there's a resolution. If the member is not reasonable and Hell bent on creating problems. I give them a holiday or send them on their way. Those ego driven troublemakers are always very driven to destroy your site's reputation when they don't get their way.
I have found in the sites I have worked on, that the "elitist" members are most often not knowingly causing trouble. I learned that a quick PM that is very serious notifying them of their actions and telling them that they are on very thin ice often solves the problem.
Yep, had it happen to me this year with one person who I considered a good member and a friend. They turned completely different after starting their own forum.