There may be no such thing as a free lunch, but Wikipedia isn't kidding about its third pillar: "Wikipedia is free content that anyone can use, edit, and distribute".
Defining freedom in copyright settings is sometimes tricky—"free as in beer" means there's no charge, while "free as in liberty" means you can do anything you want. Wikipedia is both: all of the text on Wikipedia and many of the images can be used elsewhere for ANY reason, and all that's asked is that you credit your sources.
Why is Wikipedia like this? It helps to know that site's creators were inspired by the [Free software movement] and [open source movement], which also inspired the creation of the free operating system Linux.
While this has helped Wikipedia grow, in some ways it has also held it back.