bitcoin, or any currency for that matter has only the value that people give, which "FAITH". Paper money or crypto currencies have no intrinsic value.
In the case of Steemit, they are distributing before cashing, in other words, they are giving what they don't have, and that can only have two explanations, either they have a money reserve, or they are running on the hope that the system will work and people will be buying Steem.