Actually this is a not a perfect answer.

It is correct, but probably your friends would like to figure out why STEEM is worth anything. There is so much valuable content in the Internet, but somehow people are not earn money on that. The question is: From where the initial value (measured in dollars) came from in this project.

I like to explain this in this way:

This is easy to understand, that there are some people which pays facebook or google to promote their content, because they know that thanks to that they can earn even more then they spent - promoting content can be used as leverage.

I am not saying that Steem has value because of that, but with that said, it is very easy to explain, how social media platform can make a profit, and that having a share in profitable organization is actually pretty great idea.

So... Steem is worth more and more because not mandatory investments of average users, which belive that is good idea to invest in product which provides a value, which is great content.