For the first mover advantage to have importance in technological fields, it has to have technological superiority, control of resources or high user switching costs.
As I see it:
1) Bitcoin is technologically inferior.
2) Bitcoin isn't the sole representation of this specific idea or technology.
3) Switching costs would be trivial for services and users to switch to new cryptos.
Reading your last line somehow linked me straight to Star Wars and "You don't know the power of the dark side!". First mover advantage is more prominent in inefficient markets, where marketing is valued higher then technological advancements. Technological advancements are stagnant in markets like these, because the majority consumers aren't educated enough to understand them. They will only react to smart advertisement to which the first mover advantage is most important.
I know that the first mover advantage is a force to be reckoned with, but I strongly doubt that it will be the main force that will be driving this market. The first mover advantage can direct the success of carbonated soft drinks and detergents, but the field of cryptocurrencies will be on another league from something this primitive.
Thank you for pointing out the main argument that supports the success of bitcoin.