The default client is just an open-source project on https://github.com/bitcoin/bitcoin https://github.com/bitcoin/bitcoin Everybody can start using their own

The default client is just an open-source project on https://github.com/bitcoin/bitcoin https://github.com/bitcoin/bitcoin Everybody can start using their own fork of the currency, but it's in your interest to use the same version as everybody else. You basically have to convince both miners and major stakeholders that a change to the code is good, otherwise you risk a network split, the valuation crashes and your investment is gone