When someone can't make their art work, there are a few possible explanations.
- They haven't finished learning it.
- What they learned is wrong.
- Nobody could ever possibly make it work (AKA "not my fault").
In order to protect their self-esteem, some people will struggle to convince everyone of option number 3. Because only by successfully convincing others, can they conquer their own insecurities.
(Observation courtesy of Eric Hoffer, one of Bruce Lee's favorite thinkers.)