There are only a finite amount of Bitcoin.
Per wiki: In a fully decentralized monetary system, there is no central authority that regulates the monetary base. Instead, currency is created by the nodes of a peer-to-peer network. The Bitcoin generation algorithm defines, in advance, how currency will be created and at what rate. Any currency that is generated by a malicious user that does not follow the rules will be rejected by the network and thus is worthless.
BTW, anyone planning on mining for bitcoin....save your time. Even in mining groups the algorithm has become so large that most likely you'll spend more on electricity to power your computer than in bitcoin return.
To possibly get rich, sink 10/20 bucks into emerging cryptocurrency and keep your fingers crossed one explodes like bitcoin.