At the 50th  reunion of my 8th grade Catholic school in August, I found that of  the 30 some who attended and the 10 or 15 who responded otherwise, only about 20% still went to Mass and trust me, we were catechized.  Most shocking were the women who left right after graduating from high school, many of who were VERY  devout in school.  Likewise, many of the devout men left.  My wife, who is 9 years younger than me was  surprised and asked a couple of my classmates why they left. Their answer basically was  "we were catholic because our parents were and we were afraid of being punished by the nuns if we didn't do what they said."  THAT'S IT. You can't MAKE  some one believe. You can't force faith.
I am also sick of hearing "they were poorly catechized". Please stop thinking that catechizing  someone makes them a believer.