Yeah i always wondered the same. Its just a hobby like everything else. You have to be rly rly rly addicted to actually cut out the irl social life.
because hardcore gaming needs a lot of time. And among the best players out there (you, bjord, phyrex, etc...) you need really a lot of time OR really a lot of talent... at least since you get so comfortable in a game, that you can take a month break and come back at the same skill level.
i play maybe twice per month now, but i noticed i can still say my word in a duel or in a siege... but not even near to the days i was playing a lot.
so, often casual gaming is average gaming while addicted gaming is often hardcore/pro/elite gaming.
an example in warband could be those guys having the same char, the same build, the same gear for an entire year, playing and dueling with it for that much time... sooner or later you'll get to the top.