I actually think having a fixed known supply is a disadvantage of BTC. Gold inflates at 1.5% per year. This low inflation allows gold to satisfy new demand, slowly. BTC's eventual zero supply will make BTC always volatile. There would be no BTC rush to find a new supply. While this could be good for your Store of Value, it creates volatility. Volatility will prevent BTC from being useful for transactions. It will remain a Store of Value and a very volatile speculative asset.
I think you don't understood BTC that much, if you think about it BTC is also affected by the law of supply and demand it really matters that we as investors or holders know that there is a fixed supply because it helps us when to buy or sell our current BTC holdings, if you read the article link by thenewanon135246, it helps you in understanding.
Here is the link