And that's just it, the real benefit of pools. There is a real tangible benefit to returns NOW rather than possible returns later. The two are not equal in an accelerating growth model.
That's a bit rhetorical. Just as gmaxwell wrote: there is no
sure return "NOW" in a pool vs. an
uncertain return in a distant future for solo mining. There is just a trade-off between probability and payout. There indeed is a risk to never see a block before difficulty hits the space age. But there is also a chance to find multiple blocks during the current difficulty and get a large payout. A pool doesn't pay you better in the latter case, solo mining does.
Having instant benefits now instead of later might be a huge benefit during accelerated growth of a whole
economy. But Bitcoin is a
currency and does not earn you interest. Getting 50 BTC now or later is of no difference if it is BTC's value itself that is growing. If mining would return another currency, say Batcoin, and your goal was to participate in Bitcoin's growth, instant payout of Batcoins would be important, so that you can convert them to Bitcoins before the price (Batcoin/Bitcoin) increases. But the payout is denoted in Bitcoin already, you participate in the growth of its value, even if you aren't cashed out immediately, because the return is always a nominal 50 BTC.
It would be different if the price of Bitcoin was falling and you always sell your coins immediately to earn interest in another currency. Then an instant payout would be a benefit.
How is it rhetorical if no one seems to accept it. There is a sure return now because pools of a certain size do not go full difficulties without block solving. There *is* no sure return of any kind with solo mining. if difficulty were constant perhaps, but as it jumps up up up your time to hash keeps increasing. Getting 50 BTC now or later does not make a difference except that the longer it takes you to actually GET that 50BTC the less likely you are to command similar returns to pool payout. This is why its not rhetorical?
The idea that the lottery will reward you more handsomely in the future is just wishful thinking. Yeah you
could find like 20 blocks in a row at 20mil difficulty with 500MHash/sec, but you really aren't going to.
This isn't rocket science. You have a probability curve that models your expected time to solve a block that keeps getting shifted away from where you are as time passes and difficulty increases. This is what bugs me about people saying "oh anyone CAN find a block at any time!" Yes, and anyone can win the lottery, it is still a stupid investment if the odds are stacked against you. Spread your timeline out, and you will see the advantages that grabbing as much as possible for yourself as soon as possible will yield. it's simple.
Again, i will use myself as an example to make this less abstract for you:
i have been mining for 2 months more or less. in that time i have solved 0 blocks. i have earned roughly 350BTC in that time. this means going forward i would need to solve > 7 blocks just to catch up to myself. the next difficulty (occuring in about 2 hours) will be about 1.4mil. The average time to find a block at this difficulty is 14 days at my current hash rate (> 1 difficulty change). Coin toss @ 9.75 days. The chances of me dropping 7 blocks in a row in this time period are astronomical against. Obviously i'm an unlucky case, but i'm also a real case. Again increasing difficulty isn't just some boogeyman, it's a real consideration and why you need to consider the coinage you can gather now as superior to ones you imagine getting in the future.