One name I still remember strongly was "Ratimove". And as far as I remember, he used to add useful topics to his thread (I think his thread name was 'Encyclopaedia CMIIW'!) so that newbies could get useful information in a quick way, but sadly we lost that gem, and he passed away.
Ratimov had his nickname changed to
Symmetrick, went kinda nuts, started name calling, deleted every post he could, backed out of a sponsorship, and eventually
was banned. He single-handedly destroyed his reputation and left.
I think it's now two years since the user Ratimove (Symmetrick) left the forum, and the forum moved on without them and many of them that left the forum as well.
My main problem with Symmetrick is the fact that he deleted almost all the possible valuable posts he made that are useful to newbies; he could have left the posts to benefit the forum users since he made them for the forum, but since he decided to delete them, he became less valuable and was forgotten so easily by the forum users regardless of all the good contribution he gave newbies and other community members.
Many users left the forum and will still always be remembered because they left a good legacy of knowledge to the forum; users like o_e_l_e_o because of the contribution he gave to the forum in making sure we value our privacy, and other members that were very good and shared good knowledge with the forum.
Therefore, no condition is permanent; members will come and go. Let's focus on how we can help others.