He thought to himself, "I'd doesn't even matter if they can get away with it. They can do it if they are mad enough. They can attack me if they get desperate enough, so I think it is best to nip this problem in the bud."
He doesn't know what they have in mind, but he doesn't want to experience it, especially if they can get away with it. So he told his die-hard fans that some people wanted to take his life.
He might have exaggerated a little bit, but he didn't think it was wrong to do so. He was doubly sure that it was the right thing to do when Jade began sending him angry messages about how he was playing dirty.
He has fans from every walk of life. Some of them are from his dojo, and some of them were gained through his books.
His wide range of influence meant that he had fans in various families and sects. So he got to see what would happen if those fans began to work together to eliminate a vulnerable target.