Yes 'heroes'. LPZ is not that. He is a character and a tragic one at that.
The value of Bixie was never the issue. If it became less valuable then people like YBQ would just find something else to fight over.
DFBB had clawed his way to be second in command of the Sun/Moon sect but still usurped RWX, showing his ambitions and lust for power. Only after he started studying Bixie did his ambitions die down.
Time of study. DFBB had it for years YBQ a few months.
Yet Lin Yuantu studied the art and did not turn evil. Only logical conclusion is that the art itself is not evil but the individual was.