Ok, there is exact fiat value to online brokerage accounts, why cant we use this to buy coffee? Yes, theres some volatility in value, but isnt that volatility less than bitcoin?
The answer to the above questions is because FIAT / CASH/CREDIT is plentiful, expendable and is worth less over time. Fiat currencies, over time, buys less and less goods and services as the years go on.
Bitcoin however, rises in value over time (it is a deflationary currency), this is a store of value asset that people want to hold and save, like a house, stocks, gold. People don't buy coffee with these other things. You CAN still scale bitcoin indirectly like fiat credit using 3rd party intermediary such as bitcoin equivalent service of Visa or Mastercard without needing to make any changes to Bitcoin code.
Just to re-emphasize, I go into why this is here: "Hacks & puppets & forks - how to destroy bitcoin":
https://bitcointalk.org/index.php?topic=1834310.0