As far as I can tell, when people spend more time with other people, then they are seen as fundamentally good, as 'good' is defined as having the world's well-being as a goal. If you spend time alone, then there are two options available: One, you want the world's well-being, and have discovered that it is best for yourself to not exist in the world, which would mean that you, and the world, should regard yourself as a detrimental influence. Or two, you do not have the world's best interests in mind, and only think of yourself, which by the previous stated definition would make you 'bad'. This line of reasoning does not take into account the people who socialize for selfish purposes, but as that accounts for a majority of the extroverts, I believe that no one wants to accept such shortcomings in themselves, or in the world as a whole.
So, those among us who prefer to procure enjoyment from our own lives, rather than sucking it from others, are seen as the enemies. Unfortunately, as introverted people don't often work together, I believe we will continue to be persecuted.