Miners measure revenue as income per unit of hashing power over time, a figure that moves with two independent variables. Understanding which is moving explains most changes in mining economics.
Revenue is shared by proportion
A network issues a fixed reward per block regardless of how much computing power is competing for it. Total issuance is set by the protocol, not by participation.
Each miner's expected share equals their proportion of total network hashrate. Adding machines increases an individual share while leaving total issuance unchanged.
So when the network as a whole grows, every existing participant's share shrinks even though their equipment performs identically.
Difficulty enforces the schedule
Difficulty adjusts so that blocks arrive at the target interval despite changes in total hashing power. Rising participation raises difficulty and holds block production steady.
That adjustment is what converts added competition into reduced per-unit revenue. Without it, more machines would simply produce more blocks.
Because adjustments occur on a schedule rather than continuously, revenue per unit steps down at defined intervals rather than drifting smoothly.
The second variable is reward value
Rewards are denominated in the network's own asset, so revenue measured in dollars depends on that asset's market value at the time.
A rising asset value increases dollar revenue directly, which is usually what attracts additional hashrate and eventually raises difficulty again.
The lag between those two effects is why periods of rising prices and rising per-unit revenue exist, and why they compress once new capacity is energized.
Transaction fees add a third component
Block rewards include transaction fees alongside newly issued coins, and fees vary with network demand rather than with any schedule.
During congested periods fees can form a substantial part of the reward, and during quiet periods they contribute very little.
Fee volatility makes short-term revenue noisier, and its growing importance matters more as scheduled issuance declines over successive halvings.
Why costs decide the outcome
Revenue per unit is only half the calculation. The other half is the cost of producing that unit, dominated by electricity and by the efficiency of the hardware.
Machines with different efficiency ratings reach unprofitability at different revenue levels, so a decline removes older equipment first.
That removal reduces network hashrate, which lowers difficulty at the next adjustment and raises per-unit revenue for whoever remains, producing the self-correcting cycle the mechanism is built around.
The correction is not instant, because difficulty adjusts only at scheduled intervals. Operators must therefore fund losses through the interval between conditions deteriorating and the adjustment arriving.