"I've got my ways of getting through it"
When you do go to things, you have methods. Perhaps you arrive forty minutes late so that the room is full and nobody notices you come in. You might stay beside the one person you know well, or keep your phone in your hand and look at it when a gap opens. Some people drink the first drink fast, or rehearse sentences before saying them. Others offer to help in the kitchen and stay there, or plan their exit before they've taken their coat off.
I've called these props. Therapists call them safety behaviours, and they've been studied. In the first of McManus, Sacadura and Clark's studies, people with high social anxiety reported using more of them, more often and in more situations, than people with low social anxiety. Both groups thought the behaviours helped. In the second study, as the last chapter mentioned, the researchers compared a social task done with and without them. With the props and the inward focus, things went worse.
I can suggest a few reasons why. The first three are reasoning of mine and of the clinicians who write about this, and the experiments didn't measure them.
Props take attention. Rehearsing a sentence before you say it means you're not listening to the person talking. Monitoring your escape route means you're only half in the room. That feeds straight into the blankness of the last chapter.
Props can make you seem less friendly than you are. A person looking at their phone, standing a little back and giving short, careful answers looks uninterested. Other people respond by leaving them alone, and being left alone feels like the rejection they feared in the first place.
And props steal the credit. If the evening goes fine, you conclude that it went fine because you stuck by your friend and left by nine. You never find out that it would have gone fine anyway. So the next event is as frightening as this one was, and you need the props again.
Alcohol deserves its own mention. One drink at a party is ordinary, and I'm not against it. But if you can't face a room without drinking quickly first, the drink is a prop, and it has the same fault as the others. You come home believing the alcohol got you through. It also has faults of its own, which you know about.
Not all props are equal. Helping to carry plates is a perfectly good way to have something to do for ten minutes, and hosts are grateful for it. What matters is whether you're doing it to join in or to hide. Chapter 17 suggests dropping props one at a time, beginning with the easiest. You don't have to walk in with none. If you go with one fewer each time, you'll gradually find out how you manage without them.