And why new people won't want to spend that much money into bitcoin, if they saw this thing appreciated 10 times per year averagely
This kind of thinking stems from the fallacy that consumers have no time preference. In fact it is the time preference which ultimately will lead the consumer to spend their bitcoins. They will spend less if they think bitcoin is undervalued - and more if they think it is overvalued. But the time preference is created by their consumption needs. Their spending behavior sends the correct signal to the merchants, which indicates the correct time preferences and lets them adjust the prices for goods and services.
On a similar note, some have argued that the paradigm of nominal price stability is coming to an end, because it can only be achieved by massive interventions in the money supply, which has negative effects on price discovery itself (prices have to fluctuate and change to reflect differences in productivity and time preferences of consumers). The inflation target of the FED is just a guidance for consumers to value consumption over investment (i.e. give the spending NOW a higher preference), but it corrupts the discovery mechanism in the process.
People who claim that bitcoin has a liquidity problem do not understand that the utility of a medium of exchange (money) does not depend on the overall supply, if you allow the pricing of goods and services to adapt.
Volatility is absolutely caused by supply inelasticity. Which is why we have not really seen the limits of volatility. The inevitable conclusion of that evolution is a bifurcated exchange market.
Yes - the inelasticity causes the demand for money (capital) to translate directly into price fluctuations of goods and services. Albeit a feature, it can create strong oscillations and pricing confusion. Especially when preceded by strong misallocations of money. Debt based or fractional based instruments like bitcoin ETFs can act as a buffer for short term volatility and help stabilizing the price in the short term. It is important that those instruments are regulated properly, otherwise it is an invitation to do accounting fraud.