One possible reason is that demand is partly driven by speculators.

If the Hard Rock were to put out issues of 10,000 chips you would guarantee that everyone who wanted one could get one. With that guarantee only collectors who wanted the chip in their collection would have a reason to buy and keep one. But if they only release 500 of the chip, collectors will still want one but I also can sell them to speculators. SO ideally I want to find the number of chips where I can maximize sales by also being able to sell to speculators.

Plus if the perceived rarity of my chips drives prices up on this issue. The next issue is more likely to be successful and hopefully over time this will allow me to raise the number of chips I am selling without killing the demand.

TY did this with beanie babies. They created an artificial scarcity to fuel a secondary market with stories of a $4.00 stuffed animal selling for $10,000 and this fuelled their sales of their new releases (often with rumors of an impending retirement).