Exactly. Coinbase takes your money but doesn't buy BTC for several days, so if the price goes down, they pocket the difference. If the price goes up, they will often cancel your order. It goes without saying that bitcoins are volatile so this isn't such a rare occurrence.

https://www.google.com/search?q=coinbase+scam

That's not what sanswork was saying. sanswork was saying that the buy price is higher than the sell price, so coinbase makes money off the price difference.

I don't think they intentionally cancel transactions as a way to make profit. You can see reports of them cancelling transactions when the price goes down as well but still refunding the full previous amount.

I also have an instant account so I can immediately get my funds with no chance of cancelling.

Thanks for the clarification. That's what I get for starting a comment with the equivalent of "This."

As to the accusation you can see is thrown around all over the place, that is possible, but my interest-free loan to them of several thousand dollars left a sour taste in my mouth regardless and it wouldn't be hard for them to make some money off of the capital, in BTC or not.

sanswork is talking about the difference between the buy and sell prices:

https://www.coinbase.com/charts

Transactions on a exchange shouldn't have a spread as only matched orders are executed.

Coinbase is a payment processor acting as a market maker for their clients in which case they charge a spread.

If you try to build a pure exchange this isn't an option.