At 10 cents it is cheaper than debit card transactions. And credit card processors charge 2-3% on average for transactions... maybe as low as 1.5%.

Visa is more convenient today but it took decades for Visa to get to the scale and scope and convenience it has today. If people start parking more money in crypto and using crypto credit cards it's only a matter of time before merchants start accepting direct payment from coinbase wallets. At that point, Coinbase can bypass Visa and charge a fraction of the fee for facilitating the trade from USD to BTC.