It's really not that hard to understand. First off, you can't make the assumption that that what we see of rappers is their entire personality, as we only know them from what we see when THEY KNOW the cameras are rolling. Do you know Jay z personally? no, so how can you say that he's lame? Because you've seen interviews? You act as though interviews are casual conversations. The questions are pre determined and the rapper's answers are calculated in most instances. Some rappers are comfortable being themselves in interviews and others, like Jay Z, answer the questions and KIM, either way, almost all rappers try to keep them as "formal" as they know how, which works worse for some than for others and causes them to come off as lame
Now assuming that what we've seen of Jay Z is the real Shawn Carter in his entirety, which is highly unlikely, I specifically called Gucci a charismatic rapper, not person. The character he and Jay Z portray in their music are charismatic figures, and that's why people like Gucci to answer your original question. Now whether or not that's their real personality or character, we don't know, like I said, rappers can display their personalities through their music, so it might just be them being themselves, or they might just be what you consider to be "lame" outside of rap but the character they've crafted has charisma. Regardless, a rapper's main objective is to entertain and perform, and if they're charismatic whilst doing so, than people will be drawn to them and it will show, like it has with Gucci.
I'm done trying to explain this to you, at this point, if you still don't get it, then you're either slow or being purposely obtuse.