Sir Arthur Conan Doyle thought that he had gotten rid of Sherlock Holmes. He killed him off in The Final Problem, in The Memoirs of Sherlock Holmes. Doyle was tired of Holmes, and wanted to get on to serious writing. So, at Reichenbach Falls, Holmes had a final confrontation with Moriarty, they wrestled at the edge of the cliff, and they both fell to their deaths into the falls. Watson deduces that, since neither Holmes nor Moriarty came back down the only path from the falls, then both must have died. The end.
But, the public, and Doyle's publishers, had not had enough of Sherlock Holmes. And Doyle reluctantly brought him back to life. In The Adventure of the Empty House, in The Return of Sherlock Holmes, we find that Holmes had survived the fight at Reichenbach Falls. He had rock-climbed up the cliff, and that is why he didn't come back down the path from the falls. Once Watson had left, he climbed down, and went on to explore the Himalayas, letting Watson (and therefore, the rest of the world) think that he was dead. He did this to avoid his many enemies, one or the other of whom, he says, would eventually kill him. Makes sense.
But, while Holmes was waiting for Watson to leave, one of Moriarty's men tried to kill him, by dropping a huge rock on him. So one of the criminals knew that Holmes was still alive. And, one would assume, eventually the entire criminal world would know that Holmes was still alive. Only Watson, and his readers, didn't know that Holmes was still alive.
Holmes' explanation, that he faked his death to protect his life, doesn't make sense to me. Certainly, he hides to protect his life. But, he doesn't have to be "dead" to protect his life. His faked death only affects Watson and his readers, and is needlessly cruel to Watson. It doesn't make sense.