All the free content you and I provided is our way of giving back to the community that answered our questions.

That content generates value for SO, but they do provide the infrastructure we use for free to get our problems solved and questions answered, so it seems like a fair deal to me.

If you didn't want anyone to profit from your answers, you shouldn't post them. If your answer is reasonably popular, you can bet it will be used in a product that makes money without you ever getting compensated for that.