As Bitcoin mining difficulty reaches an all-time high, the structural polarization of the mining industry is becoming increasingly evident.
While the increase in difficulty is accelerating the exit of small miners, it is also having a positive effect on network security.
Bitcoin mining difficulty ended the year at 148.26 trillion as of December 25, 2025. This represents a roughly 35% increase from the 109.8 trillion at the beginning of the year, demonstrating a significant intensification of mining competition throughout the year.
According to industry sources on the 30th (local time), the Bitcoin network hash rate increased by approximately 34.5% throughout 2025, peaking at 1,151.6 terahashes per second (TH/s) in October. Bitcoin's difficulty automatically adjusts approximately every two weeks based on 2,016 blocks, maintaining an average block generation time of 10 minutes.
During the Bitcoin price rally in September, mining difficulty rose sharply and remained high even during subsequent market corrections. The hash rate peak coincided with the Bitcoin price rally to around $124,000 in October, but the price subsequently fell by approximately 30%, currently trading at around $87,000.
Rising difficulty is accelerating restructuring in the mining industry. As the computing power required to earn the same block reward increases significantly, miners using older equipment or in regions with high electricity costs are facing profitability constraints. In some parts of China, there are observations of increasing uncertainty in the mining environment, and in North America, rising electricity costs during the winter are also a burden for miners.
In particular, with Bitcoin's price corrections occurring significantly since October, the simultaneous rise in difficulty and price adjustments is further increasing the operational burden on small-scale mining operations. Conversely, large companies, equipped with relatively inexpensive electricity and the latest high-efficiency mining equipment, are expanding their market share as competitors leave, leading to a growing concentration in the mining industry.
However, there are also positive assessments regarding network security. As mining difficulty increases, the massive computing power required decreases the realistic possibility of a 51% attack, where a single entity gains control of the network majority. This also limits the risk of a large-scale influx of mining resources into the market.
An industry expert analyzed, “The current Bitcoin mining industry has moved beyond simple competition based on scale and has entered a phase of competition centered on efficiency and cost structure.” He added, “In the short term, the exit of marginal companies is inevitable, but this can be seen as a process of strengthening network stability and improving the profit structure of surviving companies.”
