"Extroverts rely on dopamine[1] in their brain to stay happy, if a person is an extrovert with social anxiety they will likely still need that dopamine fill from other sources. Such as engaging in online group activity, listening to human voices, have multiple noise going on, doing shopping/gambling/stimulating type behaviors/stimulating music in order to get their dopamine fill, otherwise they can get into a depressive mood.
Introverts rely on acetylcholine to stay happy, over abundance of dopamine overwhelms introvert, so the true introvert needs quiet, peaceful moments with steady activity/more mellow musical choice for most times, to stabilize themselves and regain happiness"