I do the same. I have an Amex Blue Cash Preferred with a high limit, which by the way is a great card for any shopper! While I only get 1% back at Hermes, I do get 3% at department stores (as well as 3% at gas stations and 6% at grocery stores). It kind of alarms me that anyone would walk around with upwards of $10k, especially in a big city, but to each their own. It's actually funny, because Amex will occasionally call if there is an expensive charge, but Hermes is smooth sailing!
I pay off my credit card every month and would never buy something for which I didn't immediately have the money.