Testosterone-Jaw here thinks that Unk has made a mistake by making financial success and fame his primary goals above art. I agree with him that wanting to be famous is poisonous, as "fame" is vague and once he had some, he couldn't cope because it wasn't the fame he wanted. But there's nothing wrong (at least in terms of goal-setting) with wanting to be rich as your primary goal as an artist. You can argue about the morals of that, but I think that it's perfectly possible to carve a path in the arts with money as your primary motivator - it worked for 50 Cent and Takeshi69 after all.
But... setting commercial and financial success as your primary goal places you under some serious restrictions when it comes to the kind of art you produce. You must be, totally, 100%, focused on what your target audience wants. You can't put your "soul" into your music if your only goal is to sell as much as possible. You have to be cynical and produce 100% what your market will buy, whether you personally end up liking the resulting product or not. Unk won't do that. He's made a (bad) decision on the kind of music he is going to make, and he's sticking to it despite overwhelming evidence that the market doesn't want it. His ego is too caught up in his product to make the kind of cynical, cash-driven decisions he needs to make to make bank. He needs to let go and view his music as a product, but he wants to be an "artist".
If you want to produce art that's personal to you, then that's great. If people want to buy it, that's great too, but if you want to remain "true to yourself" then you can't let commercial success be the primary driver of what you do. Producing "authentic" art might mean that you're stuck as a hobbyist because your music is too niche. That can be the price of authenticity. Most commercially successful artists bend their art to the needs of the market to some extent in order to put food on the table. It's a compromise. But Unk won't compromise about anything.
Fact is, nobody wants to buy music by a clearly unsuccessful wholesome white rapper rapping about how successful he is. Authenticity is everything in mainstream hip-hop and he doesn't have any. He needs to get a gimmick, or introduce more self-aware humour, or get edgier. But he won't, because that would be "compromising his art", even though by being 100% commercially driven he has committed to doing that at every turn if he wants to succeed.
This guy hits the nail on the head when he mentions Tony Robbins. Unk has swallowed the "new thought" stuff HARD, and it's one of his biggest problems. He has been told that positivity is the key to success. And whilst it's true that nobody ever achieved anything that they didn't think they could do, this "positivity" can form a horrible alliance with someone's ego to produce someone who is immune to advice or criticism. The music industry is swarming with these idiots, and they get their pockets emptied by opportunists who can spot them a mile off. The idea of "New Thought" is that the right mental attitude and extensive meditation on your goals and motivations will guide you to making the right decisions. But people like Unk mis-interpret that to mean "I don't have to think about my decisions, I will automatically make the right ones because I am positive". That's why Unk not only refuses to make the changes to his music and the way he makes and markets it to make it successful, but also reacted so badly to the negative attention that he got without thinking about how he could turn it to his financial advantage. Fuck, even Rebecca Black figured that out.
tl;dr I don't think that Unk's problem is that he's "sold out". I think that Unk hasn't sold out enough.