Has anyone made this work? I tried to make it work. Even at 10% (Discover IT category + end of year match), you can’t buy something, have it shipped to you, sell it, ship it, and make money. Any online marketplace eats your profit very quickly with assorted fees.
https://9to5mac.com/2022/10/03/chase-apple-products-redempti...
Many of Chase's credit card sign up offers provide enough points for a cardholder to obtain an iPhone through this promotion. If the cardholder does not want the iPhone, they could resell it on a marketplace. Amazon Marketplace used to be one of these marketplaces until it started restricting listings for certain brands such as Apple.
One of the routes I'm aware of involves buying gift cards from Kroger with a high cash back credit card during their frequent events where they offer extra fuel points on purchases. They don't charge activation fees on gift cards, and you can sell the fuel points accounts somewhat under the table on eBay, and then pocket the cash back from your credit card. Then you wait til black Friday or other sales, use the gift cards to buy electronics at discounted prices, and then ship them overseas to sell for a decent markup. It involves floating tens of thousands of dollars for several months though so not quite for your average individual just trying to make some quick cash.