Interesting post. Questions so I can think of your question more clearly: 1. Do you have to pay any one time fees or annual fees for that card? Do you get any kickbacks when you spend $X (like points or cashback)?

From what I know already, you are probably paying around 4% to get cash into Coinbase, no? So your btc needs to go up that much just to make up for that cost. You can also setup a recurring payment to Coinbase so it fills it up automatically (buying btc to have ready to use your visa shift card, like topping up). So it really comes down to initial fees, do they cover the costs compared to using a typical visa which gives you usually 1% back (which unfortunately is a mutualized cost between you and the merchant, as in, the merchant jacks up the prices to cover this, so really, you pay for your own points and cashbacks :)