What do you consider to be the cause that many have lapsed the Catholic faith?

As an ex-catholic, I think the church got bold after vatican II and assumed (wrongly) that all the kids born in the late 60s / 1970s would naturally follow catholicism without question. The church leaders sort of adopted an imperial Roman view and just assumed that their empire would continue, and didn't bother to make much of a case for what made catholicism the best argument for god. Now, add to this the fact that kids in Western Culture born post-1960s failed to see holy orders (becoming a priest or nun) as a good career move, and the church began to have a problem of a shortage of staff. The church also failed to keep up with the rapid changes of the 1960s (Women's Rights, Gay Rights, etc.) and stuck with their Dark Ages mentality, which lost them more followers. Then came the sex abuse scandals starting in the 1980s, and the church really found itself on the ropes.