The thing to keep in mind is that TV writing jobs (or any writing job in Hollywood, really) is at the top of the pile for dream jobs for many many millions of people. So the competition is fierce.

But with most creative careers, if you "play the game" right, you're not really competing with millions of people. You're competing with that 0.5% who actually do what it takes to get themselves over the line. They're the people who take their craft super seriously, spend years honing their skills, (in TV land) write spec scripts that show their skills, move to LA/NYC, network, etc etc etc.

Even after you do all that you're still competing with a lot of people, but chances of success do become a lot higher.