Some performers I work with get on stage because they want to be noticed. They want the attention. This is natural, and if it were any other way we'd probably have a lackluster culture of movies, music, and comedy.
That said, sometimes the attention is the goal in and of itself, and the pursuit of a craft that is hard to master falls to the wayside. (In a way, the behavior becomes fossilized). I don't mind working with these people, but the people that I'm most interested in working with are those who don't want the limelight. The ones who don't want the attention usually have the most to actually offer, in my humble opinion. Why? Because they're more sincere and reflect the mood and experience of the everyman.
Comedy is an artform that must by necessity appeal to the everyman. If you appealed only to a small contingency in the audience, you would consistently have a poor showing. So those who are the unexpected heroes are often the most well received. I guess I root for the underdog.
For all the reluctant performers out there, I offer this advice: notice being noticed. I'm sure you already do, and you probably feel a certain amount of trepidation or even disgust ("Oh, this is just stroking my ego...."). It's alright experiencing these feelings, and same for those who soak it up ("Oh, this is stroking my ego!"). What's most important is the function this serves.
You wouldn't have show at all if the audience wasn't intently interested and aware of what you're doing. As a performer you need to be aware of this feeling and hone it. You need to know when they're looking at you, even when you're not looking, as though you have a sixth sense.
There is actually some pretty interesting science out there that suggests (convincingly in my opinion) that we do have a sixth sense, the sense of being stared at. Though its exact mechanics are unknown, this sixth sense would obviously serve a very important evolutionary advantage to know if a predator was licking its lips as he watched us pass beneath him in the dark woods. As modern people who have killed off almost all the big scary animals, most people's biggest fear is public speaking. Why? Arguably because, instinctively, their fear responses are telling them that the people in the audience actually want to eat them.
I'm here to tell you, it's all true. The audience wants to eat you, but it's OK: you can afford it. In fact, you can't afford not to let them eat you. That's what they came for.