CH12: replace dated mining pool example with a timeless example

ch10.asciidoc

@@ -1798,45 +1798,18 @@ smaller share of the overall reward, but typically get rewarded every
 day, reducing uncertainty.
 
 Let's look at a specific example. Assume a miner has purchased mining
-hardware with a combined hashing rate of 14,000 gigahashes per second
-(GH/s), or 14 TH/s. In 2017 this equipment costs approximately $2,500
-USD. The hardware consumes 1375 watts (1.3 kW) of electricity when
-running, 33 kW-hours a day, at a cost of $1 to $2 per day at very low
-electricity rates. At current bitcoin difficulty, the miner will be able
-to solo mine a block approximately once every 4 years. How do we work
-out that probability? It is based on a network-wide hashing rate of 3
-EH/sec (in 2017), and the miner's rate of 14 TH/sec:
-
-++++
-<ul class="simplelist">
-  <li>P = (14 * 10<sup>12</sup> / 3 * 10<sup>18</sup>) * 210240 = 0.98</li>
-</ul>
-++++
-
-...where 21240 is the number of blocks in four years. The miner has a
-98% probability of finding a block over four years, based on the global
-hash rate at the beginning of the period.
-
-If the miner does find a single block in that timeframe, the payout of
-12.5 bitcoin, at approximately $1,000 per bitcoin, will result in a
-single payout of $12,500, which will produce a net profit of about
-$7,000. However, the chance of finding a block in a 4-year period
-depends on the miner's luck. He might find two blocks in 4 years and
-make a very large profit. Or he might not find a block for 5 years and
-suffer a bigger financial loss. Even worse, the difficulty of the
-bitcoin Proof-of-Work algorithm is likely to go up significantly over
-that period, at the current rate of growth of hashing power, meaning the
-miner has, at most, one year to break even before the hardware is
-effectively obsolete and must be replaced by more powerful mining
-hardware. If this miner participates in a mining pool, instead of
-waiting for a once-in-four-years $12,500 windfall, he will be able to
-earn approximately $50 to $60 per week. The regular payouts from a
-mining pool will help him amortize the cost of hardware and electricity
-over time without taking an enormous risk. The hardware will still be
-obsolete in one or two years and the risk is still high, but the revenue
-is at least regular and reliable over that period. Financially this only
-makes sense at very low electricity cost (less than 1 cent per kW-hour)
-and only at very large scale.
+hardware with a combined hashing rate of 0.0001% of current the total
+network hash rate.  If the protocol difficulty never changes, that miner
+will find a new block approximately once every 20 years.  That's a
+potentially long time to wait to get paid.  However, if that miner works
+together in a mining pool with other miners whose aggregate hash rate is
+1% of the total network hash rate, they'll average more than one block
+per day.  That miner will only receive their portion of the rewards
+(minus any fees charged by the pool), so they'll only receive a small
+amount per day.  If they mined every day for 20 years, they'd earn the
+same amount (not counting pool fees) as if they found an average block
+on their own.  The only fundamental difference is the frequency of the
+payments they receive.
 
 Mining pools coordinate many hundreds or thousands of miners, over
 specialized pool-mining protocols. The individual miners configure their