One barrier to shamelessness catching on as a strategy is that some people can pull it off and some people can’t. I think it has more to do with charisma than with intelligence or talent, and charisma is something that's hard to intentionally cultivate (or at least it seems to me that you can pull yourself out of charisma negative by eliminating bad habits, but I can't think of anyone who went from sub-charismatic to super-charismatic).
Expanding on being able to get away with things... Charisma is kind of paradoxical because you'd need to change so many things at the same time. Changing them one by one leaves you often worse and even less charismatic. Something that boosts the charisma of the charismatic guy may actively work against the non-charismatic one.
Charisma is kind of like the anti-fragility concept of Taleb. It's when things that would normally harm people will paradoxically strengthen you.
