You can shop on the internet without divulging credit card information. You can send money from anywhere to anywhere with almost no fee, much like e-mail lets you send letters instantly electronically. It is internet-cash.
Bitcoin Core is the the backbone of the Bitcoin network Almost all Bitcoin wallets rely on Bitcoin Core in one way or another. If you have a fairly powerful computer that is almost always online, you can help the network by running Bitcoin Core. You can also use Bitcoin Core as a very secure Bitcoin wallet.
In terms of who, the above list (which is basically a database called a ledger or blockchain) has addresses (like email) and inputs and outputs are assigned to these addresses. These addresses are owned and controlled by humans (like email).
There are already several precedents for the need for bitcoin gambling in Asia and Africa. Zynga and Blizzard have experienced pains to sell digital goods in Asia where there are not well developed credit card networks. The problem is even greater for companies without the scale to distribute prepaid cards through these countries.
Because its easier for them to yell “bitchez” than to apply themselves to learn anything. The currency debasement war is happening, and the whole WORLD is going to see what happens when every major power is gunning for the core of the planet as a price target for their currency.