Introversion and extraversion are very robustly defined and proven traits. Maybe you don't understand what they are, or maybe you're one of those people who's not strongly one or the other so it seems to you like "everyone" just has both of those, but there is no real question about whether the traits exist.
Introversion and extraversion are very robustly defined and proven traits. Maybe you don't understand what they are, or maybe you're one of those people who's not strongly one or the other so it seems to you like "everyone" just has both of those, but there is no real question about whether the traits exist.