For us introverts, socializing is exhausting in a way that's very different from being physically tired or just sleepy. For me, it's a similar sort of exhaustion that comes from doing a tedious task for a long time. The kind of exhaustion you might experience if you had to write the same sentence out on a piece of paper by hand a thousand times. Wouldn't you think twice before signing up for such an experience? I often endure it because occasionally there are really fulfilling interactions and transfers of information that happen, but most of the time I find people in social situations don't want to engage their intellect at all and so the interaction is pure tedium.