The Bitcoin supply is fixed and predictable. So we don't have to worry about inflation or it getting out if hand because of the hard-cap. Bitcoin has Satoshi's as it's smallest denomination and its becoming the standard for everyday transactions. If we calculate how many satoshis are there in the 21 million supply it would be 2.1 Quadrillion sats. More than enough for people to use Bitcoin as a everyday currency. Having no supply cap makes it inflationary just like fiat. (Unless fees are burnt in moneto reducing how much moneto there is compared to issuance) also moneto supply isn't fixed there's a tail emission that increases its supply, therefore adding inflation reducing its value.
So Bitcoin is being spent and fees are getting paid. If people slowly stop mining that's where the difficulty adjustment kicks in and helps provide an extra layer of security for those people that want to still secure the network. There will always be people mining Bitcoin for the freedom it provides.
Also try to tell me where I am wrong in this. I have deep knowledge on this topic and I love friendly debates on these things.