Why do people refer to others as FAILURES?

Why do people refer to others as FAILURES?

I read something somewhere that has motivated me so far on this journey, and it says something like 'failures are part of life. If you don't fail, you don't learn and if you don't learn, you don't change.

So why are people quick to call other people failures?If something is not working out, you can leave it and come back another time. If you think something is not for you, you can leave it and do something else. That doesn't make you a failure. It makes you a changed person, and where there is change there is growth. 

We all desire to be different things. Simon Cowell wanted to be a Formula One driver, but he ended up being a talent judge and look where it got him.Sometimes we are busy doing something that is not meant for us, and we waste so much time and energy doing it and it never becomes a success. Maybe it's time to try other things.

I know of many people who have moved careers, moved environments, moved offices, and today they are successful because of that move.So what is failure?