The first mover advantage in this case is the fact that early adopters of crypto bought BTC, because BTC was all there was.

Now that those people already have BTC, they are less likely to purchase a second coin. For one, they already have money invested in the space. Secondly, BTC has shown that it has staying power - outlasting many altcoins which came after it - which further solidifies BTC as the top contender (for now).

So, those already invested in BTC have little impetus to change from BTC to another coin == a first mover advantage.

Isn't it just as plausible that early adopters bought BTC because that's all there was, then bought altcoins as they appeared in order to diversify their crypto portfolio? It'd be interesting to find out if there are more investors in "crypto" as a strategy versus BTC specifically.

I mean, of course that's plausible. If I gave the impression that it wasn't, my bad. I was just hoping to clarify to eugeniub why BTC enjoys a first mover advantage, and why first mover advantage has nothing to do with how often "people use it in their everyday lives".

Assuming a limited amount of resources to invest, someone who is already invested in X, is less likely to remove their money from that and invest into Y, unless Y is really good. All things equal, there is no reason to move from X to Y if X came first and you already invested into X.

So, the first mover advantage for BTC is the fact that new coins need not only be equal (in the eyes of the investor) to BTC, but better enough to convince that investor to move out of BTC in favor of that coin. People who are, in addition, buying other alt coins are still solidifying BTC's first mover advantage if they do not remove their investment in BTC in favor of something else.

They use it to talk endlessly about their coins, that might be an end in itself...