Hip hop is a different world. Other music performers can be introduced at older ages...but if you aren't established by 30 as a hip hop performer, forget it. Harsh reality.
You can be underground since 16 and never blow til 30(example: Jim Jones, Plies, I think Flo Rida? But all them were known for years by hip hop heads before thier bigger records at later ages) with a trackrecord and fanbase that expanded over that time, but you ain't comin' outta no where over 30 and making an impact in hip hop.
It's also funny how people mention Jay-Z. He's prolly the only rapper to ever come out of no where at 27(and he was background working hard as hell way before that), and he's JAY frikkin Z! No one else in hip hop has money like dude, status like dude, success like dude, he's in a lane beyond comparison with "other rappers", and he's prolly the oldest to ever come out and have real longevity.
I always said i wouldn't rap past 25 and didn't. That should be what any determined hip hop artist sets as a goal. That way, by 25, if you're not so close you can taste it, you move the f**k on, cause even if you start making moves at 25, it can still be 3 or 4 years before you're introduced to the world. More Harsh reality.
Best option for a "rapper" when you get old is to start writing and discover and polish younger talent, get into other genres of music and fuse your hip hop to give your sound a longevity and crowd that will accept you out of no where in your 30s, take up engineering or producing/background music jobs, hell, even start up a label. Doesn't matter how old you are if you play the background, but how you gonna frontline coming out of no where looking like majority of your potential consumers' dad?
You can always pull a Birdman and bring out a buncha younger cats, get famous enough with them that someone would check for ya. But it will not work if you plan on frontlining.
Anyone who doesn't agree is prolly old, or know they won't make it before they get old and have nothing else to contribute to the world. FYI, I'm 32, so phukoff.