1. It's a concept made up by the music industry as a promotional tool and easy controversy for an artist.
2. It's a method conspiracy theorists (that don't necessarily believe in the illuminati) to teach people to be distrustful of their governments/authority and they use music and religion to suck people in. TBH, when I used to research the illuminati I discovered a LOT of truths about the US and the gross things they have planned and done. But at the same time, once people realize that illuminati is a dumb concept, they might dismiss all valid conspiracy theories altogether. Which is bad.