The point is that unlimited supply (fiat) can buy everything and is centralized so its value is stable and declared by the government.
While bitcoin (limited supply) isn't controlled by the gov't which has its own value predicted by its supply and demand through us . I don't know if this answer will satisfy you.
But what is the point of having a money supply that is limited like btc when another unlimited money supply can buy all of that supply
You think that by creating money the value of a unit of 100 let's say of your money will stay the same?
Nope, google Venezuela inflations and you're going to understand what printing non-stop money means.
You're going to buy the first BTC with one second of print time, the 10000th with 2 hours and by the time you want to reach your first million already it costs you more to print money than the banknotes are worth. Do you think any
sane goverment will destroy their economy just to get their hands on all the BTC? And what's next, do the same with ETH, LTC, ETC, etc. ?
Also, you really believe that banksters do whatever they want with the money the banks have in their custody? It's nice for a tinfoil hat scenario but in reality, it doesn't work like that.