It teaches you how to think? If you are coder then you might understand the deep meaning of this line said by steve jobs. You might have experienced that even when you shut down your computer you keep on thinking about the code you have written in your project and then you will try to find out the solution of the problem in another way...
You know what its ultimately increase your thinking power/process. When you enter in the world of programming you not only learn coding but also the art of thinking.
Competitive programming is the game of brain where you have to use your coding as well as your brain power.
Programming may be a challenging role and once you enter this field you'll encounter new challenges and you'll need to solve some problems which nobody has solved before or their solution doesn’t exist anywhere. At that point you're expected to return up with an answer within the least possible time using your problem-solving and logical ability. therefore the one and clear goal behind these competitive programming is “To prepare a programmer such his/her logical ability increases and he/she is in a position to write down code for the challenging situation”.
Another reason is that big tech giants of the world that is Google, Facebook. Microsoft, Amazon hires candidate through competitive programming so if you would like to urge into these companies then you actually got to get your hands dirty in competitive programming.
Did you want to know how to get started with competitive programming ? then let me know in the comment section. I will write an article on it... :D