That's like looking at ZeroCash with a circulating supply of 2 million and a market cap of $600 million & saying 'but all I see is a $6.5 billion cap' (ZEC will have a total supply of 21 million)

Unlike BTC/ZEC/Other where inflation is largely wasted on miners to reach an eventual supply of circa 20 million, PLU inflation is given as a very small rebate to potential PLU users and adopters, so the inflation is essentially a marketing tool. As PLU is faster and has no/low fees, many BTC/other users will choose to do all their transactions in PLU and it only requires a small conversion of customers to create high net new demand.

It will be interesting to see how it works in practice.