In fact, I have been always telling myself that market cap is utterly misleading. That said, I still have to add that you are obviously looking at only one side of the coin. Basically, what you tell is true, but it is only one half of the whole truth while the whole truth is that what you say can be equally applied to Bitcoin as well. We don't know how many bitcoins are actually circulated. But we know that 1M bitcoins are sitting idly in Satoshi's wallets, so you can safely discard them. Quite a few coins have been lost for good during all these years, and you should discard them too. Apart from that, there are a few whales who said that they are not going to sell their stashes no matter what. All this can heavily limit the number of coins actively used or traded to a rather low number, low enough to make you claims unreliable
but it can not be applied to bitcoin! because simply bitcoin has been open to everyone from day 1. apart from genesis block you could mine any block that you wanted up until today. this however in altcoins which use marketcap manipulation is not true. you see a coin with 80 million coins then investigate and see 72 million coins have never been released to public for sure.
and that 1M coins of satoshi is a rough estimate and even if it is true, my point still stands. bitcoin was open to anyone who wanted to mine it from the fist generated coins.
and any bitcoin whales means they have bought it like the rest of us on equal grounds and that is a big difference in my opinion
The effect is the same regardless whether whales bought their bitcoins or not, whether Satoshi's coins are public or not
And the effect is that with Bitcoin the market cap is as irrelevant (well, mostly) as it is with any other altcoin out there. The reason for such conclusion is pretty simple and rather obvious. Only a small (if not tiny) part of all bitcoins gets traded or used as a means of payment, while the majority of coins are either stashed away or lost for good. In other words, if the reverse were true (i.e. most coins were circulating), the Bitcoin price (read its market cap) would be very different from what it is now. The bottom line is that Bitcoin market cap is as misleading as those of any other cryptocurrency