We've got Michael Saylor hoarding
We've got millions of people losing their keys
We've got guys like John McAfee dying, maybe with thousands of coins locked up forever
All 3 of these are your guesses and have no way of proving any of them are correct. For example McAfee may not even own a single satoshi as he were getting paid in fiat when he was scamming people in 2017 to buy shitty ICO tokens!
How does this not end up where a very small group of whales own the majority of coins and the rest own a miniscule amount of sats, and/or progressively more and more get lost throughout time?
Why do you focus on the future and not today? Nobody is preventing anyone else from buying bitcoin and this was the case from day one when bitcoin didn't even have a price. If some people chose to take the risk and endure all the ups and downs and the FUD all these years it is not their fault for being early, it is the rest's fault for being ignorant.
Bitcoin is 12 years old and some say 6 million coins are lost at a guess..
Exactly, these numbers are simply guesses which makes the whole discussion moot.
The fact they are gone forever, to me suggests that this cannot be 'the future of money', as more and more will continue to be lost each year.
Bitcoin is not "future of money" bitcoin is a currency that people can choose to use if they want to benefit from the freedom that it offers. And to act as a medium of exchange it doesn't matter if some of its total supply were lost throughout its history.