What is PewDiePie's secret to constant increase in subscribers?

PewdiePie commands an extraordinary army of subscribers which is constantly growing. Some may say that he had a secret to his success. However, most of the credit goes to his handwork. He puts out constant videos. He constantly produces and designs new content. He creates interesting content starring himself. On top of all of this he has a major one on one interaction with the audience through live streams as well as meetups.

Therefore, he can tell his fans directly what he wants them to do and appreciates them, gathering the love and increasing his army. This is so awaited that fans wait for his screams of the games epithets, even if they are simple graphics.