Is it true that if you're not successful by the age of (X), you never will be?

[Bicoastal]

In a thread about Barack Obama's young speechwriter, someone opined that if you're not a success before the age of 27, you probably will similarly unsuccessful your entire life.

True or untrue, this hit a nerve for me. I turn 27 next year, and although I hardly qualify as a failure, I'm certainly not a success--especially not the level of success that allows me easy access to someone of Barack Obama's stature. In fact, I'm single, under-employed, and living in one of the smallest rooms in Brooklyn. Worse yet, in my field (music), the biggest superstars tend to find success at fairly young ages--which may explain why so many of them tailspin into drugs, alcohol, and messy marriages later in life. But I digress...

Now there are plenty of exceptions to this rule, even in music--for example, Deborah Harry of Blondie? She was a nobody throughout her 20's, temping and waitressing in New York, before becoming a major rock star/sex symbol. In fact, at the time of her band's first album, 1976, she was already 31 years old. And then, if you want to look at people who changed the world, look at Ulysses S Grant. In 1860, on the eve of the Civil War, he was working in his father's leather shop in Illinois, having failed at every single thing he attempted since the end of the Mexican-American War. He was 38, an alcoholic and a complete unknown. By 1865, he had blossomed into one of the most powerful and well-respected military men in the entire country--and that was before he became a two-term president.

Still, are these two people just outliers--flukes, if you will? Is it generally true that there is an expiration date for success and happiness?