I refuse to believe this. Thinking like this is why people give up, and people who give up never can make it, but if you're the person who can push through the moment of wondering 'if', then you might just be the person that makes it. There is no law that says you must be well known, or get your idea out when you're still young.
Bruce Springsteen was 25/26 before his 'last ditch attempt' album, which when you consider that most people give up at 21 shows you how ridiculous the concept is. JK Rowling was in her thirties, James Patterson didn't even start writing til in his forties, Franz Ferdinand, late twenties early thirties.
Everytime someone thinks that they won't get noticed, because it just hasn't happened by the time they're sixteen, it just fres up space for someone who was willing to pay their dues and suffer the hard times to makes it in their thirties, and one day I swear to God that will be me.