However! For PoS coins this isn't the case. We buy 1000 CLAMs, and it's 0.1% of the 1 million total money supply, say. If there's no digging, and only staking, then a year later another 500k CLAMs have been staked. But we have staked 500 of that 500k, since we are 0.1% of the staking weight. So now we have 1500 of the 1.5 million supply, and still have 0.1% of the total money supply. Sure, assuming a constant market cap the price will have decreased by 50%, but our holdings have increased by 50% too, so our net worth in CLAM has remained constant.
This argument is false because it assumes that everyone stakes all the time. Smaller holders aren't necessarily going to stake because it isn't worth the trouble. Or they will stake in a few (or as we see now, one) large pools which catastrophically centralizes the network, and transfers (likely further concentrates in practice) wealth to the pool operator via fees.
People who are actively using the coin in a transactional manner (to the extent such a rumored mythical creature actually exists) also do not stake because the network rules don't allow it.
In this way staking is NOT the same as the inflation we see in USD, BTC, or DOGE, since the newly created coins are shared out to existing holders in proportion to their holdings.
It does bear a lot of resemblance to USD. Some are able to invest and keep up with inflation but others are not. The groups largely mirror the ones described above.
and it seems to push owners to hoard CLAMS and hold them indefinitely.
but it shouldn't. Staking is "running to stay still".
It likely does, for exactly the reason you state: Staying still is better than
falling behind.