From https://bitcoin.org/bitcoin.pdf:
Abstract. A purely peer-to-peer version of electronic cash would allow online payments to be sent directly from one party to another without going through a financial institution. Digital signatures provide part of the solution, but the main benefits are lost if a trusted third party is still required to prevent double-spending.
Of course, the coins are only yours if you hold the private keys. A promise of some Japanese exchange to send you an amount of Bitcoin in the future is not the same as owning a Bitcoin.
It's pretty interesting, you should read it.
Many people in the field are very ethical and think that an improvement to the current financial system is of great benefit to humanity.