In my paper (
http://www.newbitcoin.org/documents/newbitcoin.pdf) one of my objections was that the current distribution of bitcoins is unfair. I didn't write this because I felt personally discriminated against, but I see it as a fallacy of the Bitcoin system. (Sorry, just learned a new word, 'fallacy', just had to use it.) A new insight has struck me that needs sharing.
In order to understand why the 21.000.000 limit cannot be enforced, it is important to understand that a distribution system with reward linear to the amount of work to find them (as described in my paper) is very possible. And that it is in fact the only way a cryptocurrency can be logically implemented. I'd be happy to defend that or answer any questions about that.
Latecomers to the bitcoin system will see a wealth distribution where less than 50% of its users own more than the other 50%. (Much more it seems:
http://forum.bitcoin.org/index.php?topic=8667.0.) Where they have to do half a million times (current 'difficulty') as much work as the finders of the first blocks. (Current figures, situation getting worse.) They have the option of accepting this or start a new currency or a new blockchain. But they have another, much likelier option.
At the time enough latecomers realize how unfair the distribution is (and if at that time Bitcoin has achieved any economic significance), the "Fair Bitcoin Initiative" will be founded. They will bring out a bitcoin client that is completely compatible with the specification, except that it will award bitcoins linearly with the amount of work to find them, without an upper limit. (Yes, I know, that is not completely in line with the specification. But it's not so hard to imagine how it will be achieved.)
As soon as 50% of the bitcoin community has joined this initiative (promoted by hip webshops, mining pools with a yellow ribbon campaign), they effectively rule the distribution of bitcoins. They will adopt the only logical distribution scheme. Any early-adopter thinking this will not happen, that latecomers will accept the absurdly large early-adopter advantage, is wishful thinking.
So far I have been refraining from cashing in more bitcoins than to get back my little investment. I'll give all speculators three days to realize the implications of the above, then I start cashing in some more. Anyone willing to pay me more than my (electricity) cost to produce them will be sponsoring my new mountain bike.