Can difficulty target by exploited by miner with proprietary computer? Assume a hypothetical situation where a researcher was able to develop a computer capable of 2,000 PH/s (the current network hashrate). During his first 2 weeks of mining, he would strike it rich as he would win 50% of block generations with 5 minutes per block.

After 2 weeks, the difficulty target would readjust, and this miner would no longer have an advantage.

However, for this next 2 week period, the miner sits out, waits 2 more weeks, and allows the network to re-adjust back to a higher target, at which point he re-enters and sweeps the rewards once more.

He repeats this cycle in perpetuity.

A solo miner with 2,000 PH/s seems infeasible, but what if a powerful mining pool were to pull this stunt — withdraw from mining for 2 weeks, allow for the difficulty target to re-adjust, and re-enter with a much easier difficulty?
No, for two reasons:


His advantage is always the same. If he has 50% of the mining power, he makes 50% of the revenue when he's mining and 0% when he's not. The difficulty does not change this.
In the on/off scheme, when he's mining, blocks are being found twice as quickly. So the difficulty adjustment comes twice as fast. When he stops mining, he has to wait twice as long for the difficulty to drop, so he's mining less than half the time. By forcing the difficulty up and then not mining, he has to wait an awfully long time before it comes back down -- during all that time, his mining hardware is depreciating.


I am assuming that the only thing he does is mine or not mine. I'm ignoring the possibility that he attempts to force reorganizations or does other "bad" things.