rent-a-rapper
Someone who has or claims to have the talent to further their artistic expression into the mainstream but doesn't have the drive or motivation to do so. Imagine if Tupac didn't record and get radio publicity and perform live, rather only rapped with friends or family and didn't have the motivation to pursue the art. In the same way, a rent-a-rapper may have a gifted vocabulary to which that person may attribute some skill, allowing that person to be a verbally rhythmic individual who people praise for possessing artistic skills.
Person 1: "Wow! That was amazing! Do you ever perform or record music?"
Person 2: "No. I'm just a rent-a-rapper. I don't have the passion for the art."
Person 2: "No. I'm just a rent-a-rapper. I don't have the passion for the art."