It's simply because of the quality of movies that he is doing. Eventually fans will start to ignore his movies if the content, storyline, direction, acting etc. are not up to mark as stardom needs support of good content. It is more evident now a days as the audiences have less enthusiasm for watching movies in theatre, and even lesser for mediocre looking content like KBKJ, Race 3 etc.
He needs well-made movies with high entertainment value, like SRK did with Pathaan.