Since most people are dumb or lazy, and they pay for their dumbness/lazyness
*laziness
If you're unable to sell on the exchange (which could be more restrictive than the wallet), someone would be ready to pay the 0.8% premium.
Slightly less, 0.75%
Actually, my account was just enabled for the Exchange this week. My state doesn't even appear in the list yet
https://www.coinbase.com/legal/licenses?locale=enInterestingly enough, when you buy/sell via coinbase (not their exchange) the order is apparently routed to their exchange as a "market" order.
They probably changed the way the Wallet's price is calculated then, it used to use Bitstamp's API to pull the latest price and then add in their fee
https://www.reddit.com/r/Bitcoin/comments/1mjjfb/how_i_successfully_manipulated_coinbases_price/The people who use the exchange are speculators, and they wouldn't use coinbase's exchange if their fees were out of line with other exchanges.
They're competing with Bitstamp, their minimum fee is also 0.25% (Bitstamp charges more in fees actually because they also charge maker fees)
I trade on Huobi most the time, the only fee they charge is a withdrawal fee for CNY, they don't have any trading fees. I just use Coinbase to get back to USD
![](https://ip.bitcointalk.org/?u=https%3A%2F%2Fi.imgur.com%2FTDxUB25.png&t=665&c=VJ1miUcGKggFdA)
![](https://ip.bitcointalk.org/?u=https%3A%2F%2Fi.imgur.com%2F4qRi3F9.png&t=665&c=Ep8KlZ1O9k64CA)