I had a philosophy professor who did the fun professor trick and gave us a one word final exam. The question was "Why?"

Most of the students hadn't heard the joke before so they sat there writing extensive essays and filling the whole allotted hour with philosophy textbook answers.

The B answer was "Why not?" because it's poor form to answer a question with another question.

He would have given an A- for "Mind your own business," but the A answer was "Because."

If you don't want to watch a half hour of a guy making sparks out of a piece of railroad track, you're welcome to move on, but some people will inevitably find value in knowing what kind of time and material a piece of hardened steel like that will consume in the effort to shape it to a useful
form, or, they just like watching a big grinder making sparks for a while.

Basically, because.