I can understand why some people might find presence of Dave wary because he can throw large rocks very accurately.  Well, if they are attending conferences to shake hands and smile knowingly, then they certainly wouldn't want Dave around.  But Dave's rocks are each like the Newton's apple IMHO.  You might get distracted by the blow or even get knocked out but, if you ignore all that and bite into the rock, you have a decent chance of tasting it's core which is rarely empty nor selfish and often very enlightening. At least that's the way it's been for me.