It should be instantly obvious that the figure thus obtained is quite misleading and utterly deceiving because if we were to sell all bitcoins for real, the price would crash into single digits, and below. And this is exactly how we can define (and calculate) a real market cap of a cryptocurrency at any given moment
OP, I'm not following you here. I understand what would happen if everyone dumped their bitcoin on the market all at once, but what relevance does that have to the definition of market cap? None. That's why the definition is the same in the stock market, and nobody takes into account the market reaction to any buying or selling forces. Or maybe I'm just missing your point here
I see why you are not following me here
And that's why it is important to define what market cap is, I mean the real market capitalization (capitalization as the present value, or at a certain point in time, of all coins created). If we estimate this metric in dollars, then I for one define it as the amount of dollars that can be received if all coins were sold (though not necessarily all at once). This is my definition of market cap, of the real one. In other words, it is not so much an issue of relevance as whether you agree with this definition or not
In any case, I do think people put way, waaay too much emphasis on market cap when comparing cryptocurrencies, and those rankings on coinmarketcap are misleading at best. Dogecoin has got to be one of the worst investments in crypto (even if it is a popular coin), but it has a high ranking in terms of market cap simply because of how many coins are in circulation--billions, as compared to bitcoin's millions. Market cap tells you absolutely nothing about popularity, strength of community, utility, or whether a coin is a good bargain or a good investment. Nothing whatsoever.
If you want to discuss Dogecoin specifically, I will follow you
here