We know there will be at some point in time (estimated ~2150) a total amount of 21 million BItcoin in circulation. (minus lost bitcoins etc but all bitcoins will have been mined in the year 2150 or so
So right now we have a life expectancy of about 80 years.
So even if you are born 50 years from now you most likely won't be around when the last bitcoin is mined = when all bitcoins are in circulation.
We even know at what rate we can mine Bitcoin
So my point is, this leaves us in our lifetime with an infinite supply of Bitcoin.
No one will ever have all the bitcoin in the World, therefore, Bitcoin has an infinite unlimited supply to us.
Same as with Gold. We still find and dig and mine for Gold daily, so we have a daily increase of actual Gold we can use.
Same as Ethreum- it doesn't matter that ethereum doesn't have a hard cap because same as with Bitcoin it will be constantly mined during our lifetime.
This is why I say Bitcoin has an infinite supply to every human being alive today