I would agree that it is difficult to get dental phobics to acknowledge their problem and come to treatment, but I would not agree that treating them is a waste of time and money. The actual treatment for dental phobia is quite straightforward, brief, and effective. For the mildly phobic person who goes ahead and sees the dentist when necessary, enduring the anxiety with some discomfort, treatment could make the process much more comfortable but could be seen as unneccesary. But many more severe dental phobics simply never go to the dentist, avoiding necessary treatment which leads to major dental problems down the road, severe toothaches, loss of teeth, etc. For these people, treatment could make a huge difference in their lives.
The question still remains: How to get them to come in for treatment? I imagine that preventative work could make a difference. If a child develops a positive relationship with a dentist early on, and routinely goes to benign dental visits every six months throughout the childhood years, the development of a dental phobia would seem to be less likely. Still, I would love suggestions for how to get those adults who are sitting at home with rotting teeth, avoiding the dentist at all costs, to acknowledge the problem and come in for treatment!