No I don't see the relationship. Let's assume no intrinsic value for the sake of argument. How do you get from there to "additional coins steal market cap from existing coins"?

Seems easy to craft some counterexample, like "Doge acts as a marketing campaign for crypto as a whole and will lead to net-inflows to the BTC market".

I'm just describing the plausible argument that the original commenter said didn't exist - to that end, it should be obvious that a bullish investor, who believes crypto is the future of finance, holding a balanced basket of crypto investments, might invest less in any individual coin as more potential successes appear that must be hedged against.

> balanced basket of crypto investments

That's fair, but I doubt it would deviate very much from the top 5-10, and that each of them would have significant differences from each other (ie not carbon copy clones). I would argue that most of the value in those top 5-10 was net-new and not a dilution of Bitcoin.

The notion I'm arguing against is that me creating MyCoolCoinX on the fourth page of coinmarketcap is somehow diluting BTC, any more than some new pink sheet penny stock is diluting AMZN.

Doge is an interesting case, in that it is the same tech as BTC with just some parameter tweaks. My guess is that most Doge investors are newer to the market, and wouldn't have otherwise invested but I could be wrong.