99% of high denom chips are out on credit lines.
The casinos know where and who has the chips.
In most cases the true holder of the chips can not even play them in other casinos.
There is a reg that states a casino can not cash chips unless they know where they came from and the player played in the casino. (words to that effect)
That was the basis Binion's refused to cash Stupak's chips a few years ago. Stupak won but it took a couple years and an unknown amount of lawyer fees.

Your comparission of chips to cash has no validity at all. Chips are not cash they are IOU's. The point here is IO who? The real possesser ONLY.

The poster above does not say where he got the chip but it is pretty clear, the chip is not his.
But a nice addition to his collection.