What metaphors are used in Becoming a Man: Half a Life Story by Paul Monette?

Metaphor:

"And every year they leaped further ahead, leaving me in the dust with all my doors closed and each with a new and better deadbolt. Until I was twenty-five, I was the only man I knew who had no story at all. I'd long since accepted the fact that nothing had ever happened to me and nothing ever would. That's how the closet feels, once you've made your nest in it and learned to call it home. Self-pity becomes your oxygen."