Unlike flat currency, the value of Bitcoin will keep increasing because more can not be printed into usage, furthermore scarcity and increased demand can lead to higher price level.
Fixed supply does not give value on its own, it helps but it does not do it on its own. For it to happen you have to have at least the same demand or some increasing demand over time. My point is, do you think other crypto currencies will adopt such policies to keep up, or rival Bitcoin?
There are many shitcoins with fixed supply, and they are completely worthless. If anything, we have seen more and more cryptocurrencies changing to an infinite supply model. It helps with enriching the founders and early whales. 