I believe this is one of the major reasons why Satoshi invented Bitcoin with a limited supply so that it would not devalue over time. However, the limited supply calls for every sat's continued increase in demand and value as the adoption continues to increase globally. As time goes on, every fraction of a satoshi gets more value as the demand keeps increasing, so 21 million satoshi is enough to sustain the world as the value keeps appreciating over time.
It is not even about believing bitcoin supply is one of the major reasons why it is getting this rate of adoption, aside the other reasons that gives people freedom own it like they want unlike fiat, bitcoin been a limited is why most people are cherishing it as an asset. Look at gold and other mineral resources their limitation even though not as confirmed as bitcoin is why they are been invested in. This supply limit is part of the reason why bitcoin bull run is usually after the halving, because with the halving period happening it is signaling that bitcoin supply from mining is drying off.
As for if it will be enough? I think as a currency bitcoin 21 million supply is simply more than enough, at the current ATH we do not even use a bitcoin for transaction but rather some thousands of satoshi, now should bitcoin get to $1m then satoshi can be also be spread out. But the major thing is bitcoin right now is been treated more of an asset that’s why most institutions are holding. In the future it will be hard to get a hand on it that’s why the best time to invest is now