This is a quote from the book "Bitcoin: A Peer-to-Peer Electronic Cash System" by Satoshi Nakamoto
...entirely to transaction fees and be completely inflation free.
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The incentive may help encourage nodes to stay honest. If a greedy attacker is able to assemble more CPU power than al
l the honest nodes, he would have to choose between using it to defraud people by stealing back his payments, or using it to generate new coins. He ought to find it more profitable to play by th
e rules, such rules that favour him with more new coins than everyone else combined, than to undermine the system and the validity of his own wealth.
7. Reclaiming Disk Space...