One is survivorship bias. People who die young tend to be counter cultural and have risky or downright dangerous habits. Future conservative ghouls are risk averse by definition (Trump & Biden are teetotalers for example).

Second part is them lacking the time to publicly develop their flaws. I'm fully convinced that many idealized martyrs would go the way of Kanye if they lived long enough. Nobody truly knows how Tupac, Morrison or Hendrix would react to modern politics. On the other hand, if J.K. Rowling dropped dead after the last period on Harry Potter she'd be immortalized.

Only the good die young