In this quote, Satoshi is explaining how the Bitcoin network's proof-of-work consensus mechanism works, specifically how the mining process is affected by the computational power of the machines on the network.

He's saying that the total number of coins generated per day remains constant, regardless of the speed or computational power of the machines on the network. What changes is the proportion of coins that each machine can mine, based on its relative computational power.

In other words, if you have a faster machine, you'll get a larger share of the coins mined, but the total number of coins mined across the network won't increase. If everyone on the network upgrades to faster machines, the total number of coins mined per day will still be the same, but the distribution of those coins will shift to favor the machines with the most computational power.

This is because the Bitcoin protocol is designed to adjust the difficulty of the mathematical puzzles that need to be solved to mine new blocks, based on the total computational power of the network. This is known as the "difficulty adjustment" mechanism. As more powerful machines join the network, the difficulty of the puzzles increases, so that the rate at which new blocks are mined remains roughly constant.

So, Satoshi is pointing out that the "arms race" for faster and more powerful mining machines is ultimately a zero-sum game. While individual miners may gain an advantage by upgrading their machines, the network as a whole will still produce the same number of coins per day.