Check out Trey Morgan’s excellent blog on this subject. The statistics he quotes are compelling. Also be sure and follow the links he gives in his article.
I often think about how preachers are like coaches. In the years he has plenty of talented players (wins a lot of games), he can do no wrong. But let there be a few seasons when the players are not as good (loses a lot of games), he will probably have to move on. So, why do they do it? Well, two reasons: they love the game and sometimes the money’s good. For many preachers, one out of two is just not worth the heartache.
Here’s another problem: preaching is one of the few jobs where a person with training and experience is accountable to leaders who have neither and looks to them for his livelihood. Not only are too many leaders biblically ignorant and inexperienced, they seem to have little interest in changing that deplorable situation. It is not that help is unaccessible, it is just not accessed. Go figure.