The USD comparison does not work here, because the reason the USD is used as a global reserve currency, differ from why
Bitcoin is seen as a "reference" currency. You know most other Alt coins was based on the Bitcoin concept.. right? The USD
was used as a global reserve currency, because it is backed by a strong first world economy and it is not very volatile.
Bitcoin will always be the mother of all other Alt coins, because it was the first real Crypto currency.