It seems relatively true that some people gain energy from socializing, while others expend energy to do so; extrovert vs introvert; which is what I been told is the difference between extroverts and introverts. It's not that introverts _can't_ socialize, it's just that they have a limited capacity to do so (with the caveat that there are people who have social anxiety that cannot socialize, who _also_ fall into the category of introvert).

Given how obviously true it _appears_ to be when talking to people about their experiences, why do you say that?