Why do people get mad when you talk about the amount of Jewish people in the media? btw why are there so many?

The answer is the same as why there are some many Jewish merchants. Jewish people have almost been traditionally kept out of professions already dominated by Christians, so they have gravitated to professions shunned by Christians or not yet dominated. Also, not unlike the Greek diner phenomena, as more and more of one cultural group flock to a particular area or job field, they draw their extended family into it as well.