The second Lubavitcher Rebbe, Rabbi DovBer of Lubavitch once remarked:
“An individual that does not work to improve his service of G-d in an internal way and is instead complacent in the manner which he serves G-d, is not fooling anyone but himself.
But how hard can it be to fool a fool?!”
(Sefer HaSichos, 5701, Pg. 100)