A few days ago on BitcoinTalk some have speculated that in the future, Bitcoin mining will no longer be profitable.
The analysis starts from the observation that whoever manages to mine a block currently collects about $ 300,000.
The future of mining and Bitcoin rules
Since each block contains a little less than 3,000 transactions, it collects an average of $ 100 for each transaction you confirm by placing it in the block.
Currently this limit of 3,000 transactions is not valid, so the author of the post wonders if in the future, when miners will cease to be remunerated with the premium of BTC created out of thin air in each block they will agree to collect less than $ 100 per transaction, or users will agree to pay $ 100 in commission per transaction.
Assuming instead that at most users can be willing to pay 2 $ of fee per transaction, the miners’ collection would be only about 2% of the current one, forcing them to reduce energy consumption, and therefore the hashrate, by 98%. .
Bitcoin is a 51% attack
At this point the author of the post always wonders if such a low hashrate could question the security of the Bitcoin network, since it could expose it more to a 51% type attack.
However, the scenario described by the author of the post is not necessarily realistic.
The limit of 3,000 transactions is given by the fact that, currently, each block of the Bitcoin blockchain can have a maximum size of 1MB.
This dimension can be expanded if desired, so much so that already in 2017 there was an extension proposal, which failed only at the last moment.
In the future it is very likely that sooner or later this limit will be extended, also considerably increasing the number of validable transactions per block.
It should be borne in mind that instead the block-time, that is the average time that passes between the confirmation of a block and that of the next block, will reasonably remain around 10 minutes.
It is not strictly necessary that a single transaction registered on the Bitcoin blockchain is composed only of a single amount which is sent by a single sender to a single recipient.
So-called mixing systems aggregate many different transactions into a single aggregate transaction that is recorded on the blockchain.
So it is possible that overall the fees paid for a single aggregate transaction are also much higher than the $ 2 hypothesized by the author of the post.
However, a reduction in the hashrate is still conceivable, but it will hardly be of the order of 98%. If, on the other hand, the size of the block should increase significantly in the future, it is even possible that this reduction will be minimal, or in any case limited.
The Bitcoin halving
The fact that the halving that halves the reward for miners happens every four years gives the network a lot of time for fix any problems that could emerge from the reduction of the premium itself, therefore even if any emerge there will probably be plenty of time to intervene.
The Bitcoin protocol is virtually unchangeable arbitrarily by individual subjects, but it remains modifiable if a broad consensus is gathered around the changes, as happened in August 2017 with the introduction of SegWit, or a few months ago with the approval of Taproot.
While these changes are not hard forks, but backward compatible soft forks, although a block size change may instead require a chain split hard fork, it is by no means implausible that the worldwide bitcoin community will end up accepting a similar change in the event of a need.