Problem with fame
The problem with Banksy’s level of fame was that no matter what he did, it just kept growing. The wheels were turning and there was basically nothing he could do about it. The machine stood behind him completely and the more he tried to make fun of them, the bigger he became.
On top of that, people were copying and collecting his art, and then turning it around to make a profit by using his name. Banksy just could not escape this cycle, at least for now. Perhaps in the future, he will find a way to totally crash the value of his work to make a point.