If we compare the crypto assets market to the stocks markets in general, can Bitcoin be considerated as the equivalent of the dollar?
In the stock exchage we buy shares with dollars.
In the cryptocurrencies exchanges we buy tokens or coins with bitcoins(and other cryptocurrencies, Litecoins, etc).
I think that the system is different, in case of fiat money the price of each currency is measured in comparing to one another, in crypto prices are independent. Besides, we are still buying other cryptos with dollars and other fiat money, and not only with bitcoin. ICOs most often take ETH as a form of payment.