It doesn’t happen all the time; Jesus (who has the biggest numbers of followers) was crucified. Mansoor was given poison. Socrates also suffered in his life time. You can say, these people took others’ bad Karmas over their head…whatever (I don’t believe this, bad karmas can’t be shifted from one head to another, it’s God’ justice, no one can interfere). And a mad dog doesn’t know who is spiritual or not.
But, it happens most of the time, animal and evil person don’t attack on spiritual people (Gurus); the reasons are the followings:
We know, nature is uncontrolled; animals, birds, humans (talking about body), trees, rivers, mountains, etc., all come in nature. And, this nature is none, but the composition of five elements, i.e., earth, water, fire, air and ether. And, there are three stages of every element: 1. Pure (Satoguna), 2. Semi-pure (Rajoguna), and 3. Impure (Tamoguna). Satoguna, Rajoguna and Tamoguna are words in Hindi. The nature is uncontrolled because its elements are impure.