The day you convince yourself that you've mastered your craft or profession or even your relationships, is the day you cease to live. The thirst for knowledge and the mind's ravenous appetite for constant growth and evolution helps sustain a meaningful existence. If you cease to aim higher, you will surely fall short.
The entire object of true friendship/relationships is to make people not merely do or say the right thing, but to enjoy saying and doing the right things; not merely to like, but to enjoy being admired, and not merely to love, but to love unconditionally and all their flaws.