You'll learn how to fly in many different types of weather when you have to use only your instruments.
Most pilots become CFIs so they can teach others how to fly and build hours towards airline minimums.
As the name suggests, you'll learn to fly an airplane with more than one engine, a requirement by airlines.
Federal regulations require airline pilots to have 1,500 hours minimum. Once you reach this, you can be hired.
You'll need this to fly cargo and passenger airlines. Most jobs pay for you to get it once hired.