You are a terrible singer. Since you're enjoying a successful singing career right now, I'm going to assume that nobody has had the balls to tell you that before. Have you ever wondered why all of your songs are processed heavily with auto-tuning? It's because you are what's called "tone deaf." So while you may enjoy singing, and think you're doing a good job, your voice makes others cringe. That is why your producers always make you sound like a robot. People love robots! People don't, however, enjoy listening to people who hit 0% of the correct notes.
You know how you always fail out of Rock Band when you sing? It's not because the mic is busted. It's because you're all over the place! Seriously. I saw what was supposedly a live performance of yours, and was expecting to hear the usual auto-tuned robot singing that we've all become accustomed to. Instead, I heard an undistorted performance. I've heard local bands with better singers than you! Sure, they suck, but they aren't bringing in the big bucks.
You might be asking yourself, "If I'm pulling in the big bucks with this lack of talent, why should I learn how to sing?" You are raking in the money because of your image. You're young, and I'm told that people find you attractive. How much longer will either of these attributes fit you? If you learn how to sing, none of that will matter. You will be around forever like David Bowie.
That is all for now. Tell that Chris Brown to step off...or something.