Each block that you solve has a reward. In practice, some blocks will be orphaned, so the expected reward is slightly less than the nominal reward. Each second that you delay publishing a block, the expected reward drops somewhat.

On an infinite timeline, the total reward approaches the expected reward. But reality is discrete, and zero tends to be a brick wall. If you delay publishing a block, you will get either the nominal reward, or zero, not some fraction in between. And if your personal random walk involves an excursion through negative land, you may not stick around long enough for it to come back.

Thus, a positive expected value is not sufficient for some strategy to be a good one.

Peter Todd wrote:

Gamblers ruin has nothing to do with it. At every point you want to evaluate the chance the other side will get ahead, vs. cashing in by just publishing the blocks you have. (or some of them) I didn't mention it in the analysis, but obviously you want to keep track of how much the blocks you haven't published are worth to you, and consider publishing some or all of your lead to the rest of the network if you stand to lose more than you gain. Right now it's a mostly theoretical attack because the inflation subsidy is enormous and fees don't matter, but once fees do start to matter things get a lot more complex. An extreme example is announce/commit sacrifices to mining fees: if I'm at block n+1, the rest of the network is at block n, and there's a 100BTC sacrifice at block n+2, I could easily be in a situation where I have zero incentive to publish my block to keep everyone else behind me, and just hope I find block n+2. If I do, great! I'll immediately publish to lock-in my winnings and start working on block n+3 Anyway, my covert suggestion that pools contact me was more to hopefully strike fear into the people mining at a large pool and get them to switch to a small one. :) If everyone mined solo or on p2pool none of this stuff would matter much... but we can't force them too yet.

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