What you write is what you sell, media ofcourse analyzes what news to sell for them to earn. they are saying something about what is trending to people and what could catch people's interest. If bad news trends then they will write on it, sometimes they over react on it just to catch the people's attention. Not all media are negative to bitcoin. Maybe you are also caught with what media says about bitcoin.
One more thing, if media doesn't over react on something that happens, people are the ones who over react to it. they panic, seek information regarding what is happening, asking advices and then media attacks back to a more terrifying news..
Lastly, writing news is a job, writers earn from it.