This is like complaining that the rates at the airport currency exchange are worse than in your FX trading account. Coinbase isn't a brokerage, it's more akin

This is like complaining that the rates at the airport currency exchange are worse than in your FX trading account. Coinbase isn't a brokerage, it's more akin to a bank, and like a bank you're not going to get the market rate if you want to exchange currency. If you want to use a brokerage, use GDAX.