However, if a person takes pleasure in the accumulation of money, the pleasure that can be experienced is endless
This premise hasn't really been demonstrated, has it? Even if we posit that the money is simply like trinkets you win in a board game, and you don't care about its buying power, it would seem likely that some burnout would take place. The pleasure paradox could certainly apply here, even if the timescale is longer than with other pleasures.
Also, we should distinguish between pleasure and professional satisfaction and accolades. The big money maker might keep playing the markets, not because he still derives pleasure from the dollars rolling in, but because of other things, like the esteem of his peers and a feeling of competence. Demonstrating competence brings satisfactions that seem to go beyond the pleasure paradox, because those satisfactions can sustain a lifetime of endeavors and help maintain a social network of people who also value that competence. So, in short, it's not really about the money at all, except as a symbol of capability.
To give a concrete example, I used to live in the same city as Warren Buffet. I heard him speak, on a couple occasions. He gave the clear impression of someone who had once enjoyed making money, but no longer got much thrill from it, and was more focused on leaving behind an honest and well-managed company and sharing some of his wealth with various worthy causes.