But I want you to doubt me, I don't want you to buh-lieve
Cause this is something that I must use to succeed
Em is used to being doubted or having to beat the odds, this is something he’s done for his entire career. More importantly, in order to succeed, he wants, needs that criticism about his work, so that he could use it to fuel up his passion and ambition. In other words, he doesn’t want you, his opponent, to butt-leave (pun intention incertain).
Also, he here gets going with that about-to-sneeze flow rhythm, as in withholding the first syllable of a word then spit out the rest when your sneeze turned out to be a false alarm ; buh-lieve/suc-ceed/es-teem/bul-let/a-llergic.
One could take at him for using an apparently “cheap” technique of cutting the words to make'em fit his flow, but he goes and gives it a litteral justification with the sneezing/allergy to failure-context. Clever.
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