Had a guy come into the dive shop today wanting to get his 40 yr old regulator serviced (had not been serviced in over a decade) & was of a long obsolete brand (don't remember what it was). After being told that we would not be able to service it, he looked around for a "cheap" regulator set & let it slip that he wanted to take his 8, 7 & 5 yr old grandkids diving in the family pool. Of course we suggested to him that his plan was not a good one & he shot back, "once I leave here you can't control what I do". True enough,.. we can't. We went over the potential risks, to which he would reply, " I was certified a long time ago & I'm an experienced diver". When asked how much/ often he dove, he replied that he dove once or twice a year in his pool, but had not been open water diving in over a decade. Then asked to rent a tank so that he could try to get his non functioning regulator working again. At this point knowing his intentions, we refused. Kind of a gray area, since he was a certified diver, but with knowing what he wanted to do,... it was decided that we could not risk the liability. Now, to the point,.... What are people's thoughts on situations like this? Why do these people think they have enough knowledge/ skills to teach others to dive, when they likely barely can dive themselves- I refer back to the Eagle's Nest fatalities that happened 2 yrs ago (an OW father & an uncertified son). Why are these people so willing to risk the safety of their loved ones? Although rare it is possible for someone to have a lung overexpansion injury, from holding the breath & ascending quickly in just a few feet of water. Unfortunately, this can be a very delicate subject to discuss with some people. Some you can get through to, some you can not.