Oliver thrives in chaos.
When the world cries, he swims in the ocean of tears.
When the world bleeds, he sucks up the blood to grow stronger.
When the world screams, he dances to it like it was music.
All in all, he was a nut job.
However, one thing separated Oliver from true insanity: his relentless pursuit of his goals.
While his means to achieve it were often shady and unorthodox, his goals and ideals were always reasonable. Thus, the villainous person was seemingly better at doing the job of a hero.
Unlike heroes who shy away from difficult situations, Oliver forces his way through to achieve his goal. So, regardless of his weakness, he finds ways to accomplish what he wants.
An example of it was what happened a short while ago.