Bitcoin's rules cap issuance at 21 million units and reduce new issuance over time. Nodes independently verify those rules rather than trusting a central issuer.
Scarcity alone does not guarantee value. Market value also depends on demand, liquidity, usefulness, regulation, security expectations, and the willingness of people to hold or use the asset.
Because demand can change quickly while supply is relatively inflexible, price can move sharply in both directions. Treat the supply schedule as a property of the system, not a return forecast.