Hello! Do experts need to continue to try to improve...

[SittingBull]

their game of choice. It seems to me that once one becomes an expert at a given game/structure,he has graduated and does not need to try to continue to learn/improve. After all,once he/she arrives at this expert level,what is there MORE to be learned? The expert player has already reached his full potential.
The world class no limit tournement texas hold'em player,Chris Ferguson, stated that one ALWAYS need to continue to improve his/her game--otherwise,expect to deteriorate in play.
Does this statement apply to experts too?
SittingBull