Your thread headline said "Popular First Names In The Pool World"
To answer your premise, i.e., "Hey Mike", etc, that's because these are popular names in the world, not just the pool world.
To have a popular name "in the pool world" would seem to me to mean a polpular name EXCLUSIVE to the pool world. For example, you go into your local room and yell out "Hey Triangle, what's up dog!" Or, "Hey, my man Masterchalk", or "6 ball, how you hittin 'em?" If a whole slew of guys look up at you, then you're on to something.