It is impossible to create bitcoins from thin air, that would violate the bitcoin protocol rules for keeping the supply of bitcoin at steady rate, and would cause bitcoins to become worthless.

Every 10 minutes or so, a new block is mined which creates a certain amount of BTC (currently 6.25BTC). This number halves every four years to keep the total number of bitcoins at about 21 million. By limiting the supply of bitcoins to a fixed amount, the price relative to paper money increases.