Just a year ago, on December 18, 2017, Bitcoin marked its maximum historical price, close to $ 20,000.Today, Monday, its price plummeted to US $ 3,400, so in this period it has lost 80%. This collapse implies, in terms of market capitalization, that some US $ 700 million were "evaporated".But Bitcoin is not the only one that has experienced this fall. Neither is he the most affected, since the Ethereum has fallen more than 90% from its record of $ 1,393 to the current $ 108. The same happened with the Litecoin, which went from $ 302 to $ 31.Such a collapse not only affects investors, but also causes a profound negative effect on the "mining" of cryptocurrencies. That is, about those companies or people that try to solve complex calculations to generate the different digital currencies in exchange for a reward."This abrupt reduction in activity affects everyone equally," say from Autonomous Research Fundstrat Global Advisors. And they add that this leads to "a consolidation of the market, since at least 100,000 individual miners have recently closed".As a result, it is estimated that around one and a half million servers have been disconnected since the beginning of September to date. It is that, to the dismay of many, those who manage to survive under the adverse conditions caused by this new scenario are those great players with very specific business models and extremely low electricity costs.According to analysts, most are only profitable when the leading cryptocurrency quotes above $ 4,500. And it has not exceeded that level since November 19."The Bitcoin would have to go back up considerably in price for mining to become self-financing again, as it has been for most of its history," they say from Fundstrat, a market research center based in New York.Although this process of consolidation could be considered as natural in a market so widespread throughout the world, the other side is that it involves a risk for investors and other people with acquired rights in the network."With fewer companies controlling mining, there is a greater likelihood that several may join to execute what is called a 51% attack," says Ryan Selkis, co-founder of Messari."With such a maneuver, the miners can reverse transactions and stop the new ones, which can potentially make them flee with the money of thousands of people," they warn.In this sense, they take as a close reference what happened with chains of blocks that accept much smaller coins, such as Bitcoin Gold and ZenCash, which have already suffered this type of attack.Mike Kayamori, CEO of Japanese cryptocurrency technology and operator firm Quoine, says: "If there are enough miners that go bankrupt, that means that the balance is close." When you see how the markets overflow, both upwards and downwards, You can say it's close to the bottom. ""We are entering the phase in which a market purge is taking place," said Malachi Salcido, head of Salcido Enterprises, based in Washington, one of the largest mining companies in the US, with 22 megawatts of power deployed. and 20 megawatts more under construction.Salcido argues that "only a select few can remain in the game: players with scale, very specific business models and extremely low electricity costs."As an example, he adds that "margins before expenses fell from around 40%, to less than 20% during the downturn".Simultaneously to the massive closure of mining centers, another clear indication of the problems facing the sector appears: many companies are shrinking to cut energy costs, in order to achieve a balance in their accounts.This situation is affecting especially those who have no equipment or facilities of their own and depend on others who "guard" them, but the situation is problematic on both sides of the counter.As a result of the hardening of the conditions, some equipment that was highly sought after at the height of the market is being sold second hand for recycling. But with the current costs of exploitation and production, they warn that it is better to disconnect them if the price reaches US $ 3.800, a figure not very far from the current one.On this point, Mao Shixing, founder of F2Pool, indicates that miners with older devices are opting to sell their equipment and recover to some extent the investment originally made.Other reasons cited by the manager of F2Pools are the existence of new more powerful equipment in the market, which has led to the deactivation of the oldest ones because they are not competitive enough. But this has worsened after the fall of Bitcoin, an aspect that affects the "farms" that operate with devices of the years 2016 and 2017.As explained by Dovey Wan, co-founder of Primitive Ventures, "many miners are working at a loss with the current prices, and now it is cheaper to disconnect them and remove them from the rack to reduce the cost in electricity and operating expenses.""Some owners of the most important centers say they have been operating at a loss for the last three months," he explains. The situation does not seem easy in a market that has little to do with the optimism that was lived a year ago.In this clearly contractionary context, the low profitability offered by the "irons" manufactured between 2016-2017 is increasingly evident, beyond the aforementioned increase in the costs of electricity in China.A report published by the Chinese farm F2Pool indicates that between 600,000 and 800,000 miners have stopped operating their devices in the last two weeks of November, which drew the attention of the community for the implications that this could have for the operation of the net.The otherOne of the ways to measure the speed of processing and, therefore. the associated cost is the "hash rate". It is a unit of measurement of the power of the Bitcoin network and is expressed in terms of seconds.As an example, when the network reaches a rate of 10 TH / s, it means that 10 trillion calculations per second can be resolved. The lower it is, the overall efficiency improves. On this point, the Blockchain.info portal provided some interesting information about this level and the degree of congestion.The data reflected indicate that the hash power decreased from 47 million to 41 million TH / s, registering this abrupt fall between November 10 and 24, representing a decrease of 13%.In this regard, Shixing explained that this was because many of the operators that stopped operating used older models for the activity.With the so-called "hash rate" - or the processing power in the Bitcoin network - 36% below its historical maximum in August, the difficulty in solving problems decreased 10%.This allows it to be easier for the remaining mining platforms to obtain Bitcoins as a reward for their contribution to the network.On this same topic, the eToro senior analyst, Mati Greenspan, concludes that "the Bitcoin hash rate has fallen to its lowest level since August of this year". And that everything can get even worse.