"The nature of bitcoin is that its core design has been fixed since the release of version 0.1 and will never be changed." -- Satoshi Nakamoto, June 17, 2010 If bitcoin were a central bank, it would be the world's most independent central bank; If Bitcoin were a country, it would be the most sovereign nation-state in the world.
To date, Bitcoin's resilience has not only been its success in fending off outside attacks, but also its vigorous resistance to any attempt to change bitcoin or its character.
It's no exaggeration to say that bitcoin's consensus rules dictate that no one can control it, and that people's only choice is to use it as it is, or not to use it.
An attempt to improve bitcoin
Many improvements have been proposed in the bitcoin community, most notably "scale-up," an attempt to increase the size of individual blocks to increase the network's trading capacity, but all have failed.
It's easy for anyone with programming skills to change Bitcoin. The real challenge is getting everyone on the network to accept the same changes.
Several attempts to expand bitcoin have been actively promoted by the bitcoin community.
In June 2015, Gavin Andresen proposed Bitcoin XT, which aims to increase the block size limit of Bitcoin from the then 1MB to 8MB. However, most nodes refuse to upgrade.
Then, Gavin Andresen unsuccessfully proposed a fork under the name Bitcoin Classic to increase the block size to 8MB.
In 2017, Bitcoin Unlimited, which owns the world's largest miner and is backed by the super-rich who control the domain name Bitcoin.com, failed to push the big block movement.
In August 2017, a hard fork in the name of Bitcoin Cash, a large block family, was launched to support 8MB blocks. Since then, the price of Bitcoin Cash has continued to fall and is now worth less than one-thousandth of bitcoin's value.
Since then, bitcoin supporters have been dismissive of such attempts, because any attempt to change bitcoin's consensus rules would lead to the creation of another bitcoin clone and would not really change bitcoin.
The composition of the Bitcoin economic system
Bitcoin is hard to change because its economy is made up of developers, miners and owners, whose interests are inconsistent or sometimes contradictory, and all improvements to bitcoin require the support of a large number of participants.
For example:
Developers want to add new features, but they can't force change on anyone. They can only submit code, at the user's discretion. So code that is compatible with existing Bitcoin will be easier to approve and download than code that is not.
If a change increases the rate at which new bitcoin coins are issued and increases the rewards miners receive for mining, miners may like the proposal, but existing coin holders do not, so it is unlikely that holders will agree to such a change.
One proposal to increase the block size of the Bitcoin network is good for miners (who can pack more transactions into a block and receive more transaction fees). However, long-term coin holders are unlikely to support such a change, fearing that larger blocks would make the entire blockchain too big, making it too expensive to run full nodes, thereby reducing the number of full nodes across the network, making it more centralized and vulnerable.
So bitcoin developers who want their code to be accepted had better keep the consensus rules intact; The best bet for bitcoin miners who want to earn a return and not waste the cost of mining is to follow the old consensus rules; The best option for Internet users who want their transactions to settle smoothly is to maintain the consensus rules.
The Bitcoin system has reached a stable equilibrium
Bitcoin has shown a strong preference for the status quo, and so far all that has happened are small, uncontroversial changes, and every attempt to change bitcoin on a large scale has ended in complete failure. Even seemingly innocuous technological improvements are hard to promote.
For all parties, bitcoin's current state is tried-and-tested, safe and familiar, stable and reliable -- a stable Schelling Point that encourages all participants to hang on, with great risk of loss to abandon.
Barring a catastrophic failure of the current design, a significant percentage of nodes will choose to continue using existing Bitcoin.
That pleases long-term bitcoin holders, who value nothing more than the currency's immutability and resistance to change.
conclusion
Since no one node can force the others to change their code, there is a strong collective consensus to maintain bitcoin's existing consensus rules.
This strong preference for the status quo makes it extremely difficult to change its supply or other important economic parameters.
It is this stable equilibrium that has given bitcoin its hard-currency credentials. If bitcoin deviates from these consensus rules, its status as a hard currency will be severely diminished.
Bitcoin is easy to use but almost impossible to change, and once you choose to use it, you have to follow its rules, accept it for what it is, and use the services it offers. That's why no one can change bitcoin.