Why is it impossible to forget Sherlock Holmes once you know him?

Arthur Conan Doyle murdered Sherlock, but he refused to die. He was revived again and now 100+ years later he still stubbornly declines to leave our hearts. Why is Sherlock so unforgettable and why is he so unique? Because he actually accidentally fulfils all the required criteria for a mad genius, and is in fact a classic mad genius. Here is how:

1. He was solitary. And singularly loved his solitude sometimes to the point of jealously guarding it. He liked working alone. Not because he lacked friends, but because company always hinders great minds from their minute functioning.
2. He was intensely hated and envied by the police. Not because he was hateful but because they could never get ahead of him despite their hard work and most of the times needed his help.
3. He practiced his profession not for money and recognition but for the thrill and mental stimulation it brought him. Indeed, according to his own words his work was his own reward. He often walked away with a smile on his face after having solved a case and letting the world believe the Scotland Yard solved it.
4. He was a violinist. And a weirdo. And a chemist, and a boxer, among many other things. The combination of music and science is a lethal one for geniuses.
5. He could solve complex cases just by thinking, sitting in his armchair, lost in the fumes of his tobacco carefully untangling facts from each other. When the working fit was upon him he would keep relentlessly at it forgetting even to sleep, eat or do anything. His science of deduction is solid. Anybody can follow it and would develop a sound thought process. His case studies form part of a necessary curriculum for French police.
6. He was eccentric to the point of madness, had weird habits, kept his home thoroughly untidy and disorderly, yet had immaculate manners and a catlike sense of personal cleanliness. He had no time for mundane, ordinary or dull. He craved the bizarre, the complex, the challenging. He considered boredom as a curse of his life and would sometimes suffer from irritability and depression just because he couldn't find a challenging case.
7. He was dry and cold, talked less, thought more, worked even more, had little interest in the world outside his world, money, friends and women although he was fully capable of leading a comfortably rich life. Women felt naturally attracted to him, and many would have liked to be his friends had he wanted. But despite his dryness and machine like coldness he had a very clear sense of right and wrong and kindness and cruelty. He could be relentless to criminals but could be kind to poor showing his presence of innate moral compass and a guiding higher conscience.
8. He made his own rules and broke those that didn't make sense to him.
9. He had a vast knowledge about most subjects and varied interests that had always intrigued Watson.
10. He was a workaholic. His work was his religion. Whatever he did it was with his complete mind, body and soul, and with perfection. In order to achieve the results he could go to any lengths. That included seducing a maid, and even promising to get married to her in order to glean confidential info for his case, exposing Watson and himself to poisonous fumes and starving himself to death just so he could fool his enemy into thinking he was really going to die. He regularly fooled his enemies into thinking he was a fool.
11. He was highly conceited, had a very positive self image and sky-high opinion about himself, didn't bother about who thought what about him, felt irritated, contemptuous and impatient by fools though had a high regard for simple innocent honest people.
12. Most people can't handle being defeated or challenged. He never lost a challenge. The once that he did, he ended up admiring her for her brains. Intelligent people always admire intelligence even if it comes from their enemies.