Because Trump is a dick and the press are all pussies!

Trump is a text book clinical Narcisist in superlative degree. Which means he does not care for anyone or anything other than himself. Of course his reaction is always to stop or counterattack anything that is not in agreement with what he says or does. That behavior is the product of a very low self-esteem, and since he is unable to accept that, he has to overcompensate with overinflated views of himself. And this is not conscious from his part. Narcissism is a mental illness, and as such, by definition, will not be a diagnosis that is accepted by the person having it. There is so much more to say about his narcissism. But in any case, the problem with the press is that, those outlets that are serious and professional have to pay attention too what he says because after all he has an investiture, and the outlets that are less serious just do not know what to make of his behavior.