In practice, most users don't run bitcoin software at all, but interact with service providers like Coinbase. You can also run client software that only downloads part of the blockchain and allows you to generate new wallet addresses, monitor the network, and initiate transactions. Many clients are suitable for portable devices. You can even run client software on a computer that never connects to the internet, using it to create new addresses with minimal risk that the private keys will be stolen. Bitcoins don't really change hands, they are always in the blockchain, assigned to addresses. Individuals control private keys, which give them the ability to initiate transfers from an address. The power consumption is considerable and a fair source of criticism, as the low hashes produced by all that effort have no use beyond proving that you did a lot of work.