Because computers are everywhere, societies depend on them to function, and you likely have at least one that you use every day.
Programming is the most fundamental control you can have over a computer. If you do not control your computer(s), then who does?
I believe you should have the power to control such integral parts of your life. What you choose to do with that power is up to you. Like learning to write, or to sew, programming gives you the power to control your own destiny. Want to write to your Mother? you can with the power of writing! Want to replace the buttons on your jacket? You can with the power of sewing! Want to write the next best selling novel? You can with the power of writing!
These examples are things you can do, given some skills, that affect your life.
Programming a computer is comparable to writing and sewing. It can be practical, but also creative. It can be useful and also artistic.
Ultimately programming is a tool for problem solving. In the same way making a jacket solves the problem of needing clothing to keep you warm and or dry, or writing a novel solves the problem of needing entertainment.
The kinds of problems programming solve are less tangible, but no less profound. For example how did you last communicate with your closest fried or family member? Chances are it wasn’t in person, in which case computers and computer programs were used. Even if you sent a paper letter, the postal system relies on computers now, as do phone systems.
Okay you can’t sit down and make a whole phone system in a few hours alone like you can a jacket, but you can’t very well take raw cotton, metal ore, trees, and stone, and make a jacket factory yourself. You can make a part of the phone system though, or help improve a part of it.
If you’ve every used an Android phone, Firefox or Chrome web browsers, or services like Wikipedia, then you have used free software. Free software is usedeverywhere and is made by people all over the world. Writing free software can be a career or just a philanthropic hobby. Free software is created by corporations and individuals alike, and programming is a tool to be a part of these solutions to societies problems.