Cause can't nobody tell me what I ain't gonna be no more
You thinking I'mma fall, don't be so sure

from J. Cole – Sideline Story Lyrics on Rap Genius

Meaning

Implying that since he’s made it, no one can tell him he won’t make it, or that he won’t be a “ somebody ” .

Also stating the fact that people think he’ll fall from the top and become washed-up.

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