The same qualities that make a stock or asset desirable (appreciation) make for a bad currency. The expectation of wild appreciation discourages transaction and encourages hoarding.
This is one of the the reasons why (low) target inflation rates exist. The (slight) devaluation of the currency encourages consumption or investment with the currency and discourages mattress stuffing.
Monero has infinite (but low rate) tail emission, meaning the unlike bitcoin the supply approaches infinity. Unless the basket of goods Monero can purchase also goes to infinity, Monero at some point will have inflation.
In most economic models, inflation is not defined as being equivalent to the growth of the monetary base (although that does not stop many Bitcoin and other crypto proponents to claim it is).
In fact, a currency with a constant rate of issuance is actually highly deflationary in a growing economy.
The potential (not actual) Monero supply will surpass the Bitcoin supply in 2044. Lost keys may exceed emission, which would imply deflation of actual supply.
Are ‘cryptocoins’ currency or speculative assets. Both ideally need some diametrically opposed properties; stability vs increasing value at the very least.
If I had a dollar that would triple it’s value in a week “just because” I would be suspicious.