Heard it many a time, but to each their own reasons for the lifestyle they choose,
I know a fair few people that live as introverts due to a phobia, injury, worklife, etc, and its not an issue for them, they (usually) have everything they want or need and lead happy lives.
Hell, some people are BORN to be introverts, as a study we conducted during my basic training during my stint in the forces; and those people tend to be the better of the two, able to lead their lives with more 'effective results'.
Me personally, I don't go out and drink with my old mates, its draining a waste and to me, they seem not to be having as much fun as I do with my small cadre of close mates that'll play cards, have a BBQ, goto the gym and generally do things that people consider 'stupid, lifeless things'.
I enjoy myself most days, can half of the people that say to me "Get A Life!" say the same? no
Operation Rant: Complete