21 million bitcoins will be supplied over 18 million bitcoins have already been mined.
Well over 19 million
BTC has already been mined at this time.
Bitcoins value as you pointed out is tied to its qualities which people benefit from holding it - this is what drives demand.
I desire a decentralized, transparent and immutable asset which can be transferred across borders seamlessly and without the need for a third party, so I desire to own bitcoins.
The supply which is finite would not grow against demand as I pointed out in a reply few minutes ago. This means demand is the only variable and supply is constant or rather limited. This drives the value.
bitcoin is not a scarce resource
there are going to be 2,099,999,997,690,000 sharable units. these units combine at a rate of 100,000,000 to be a basket term called a (btc) bitcoin, meaning bitcoin is devidable by 100,000,000 units
yep enough units for all 8 billion people to have some division of a btc
Being divisible does not make a product less scarce. Everyone can get a share of Bitcoin, but everyone is limited in the amount of Bitcoins they can own due to its limited supply.