You don't buy food with miles. You win cookware sets. The best you can do to convert them in money is to trade them, but to obtain them you still have to buy

You don't buy food with miles. You win cookware sets. The best you can do to convert them in money is to trade them, but to obtain them you still have to buy them or flight for real (proof of work IRL) But there's no largest marketplace on earth, controlled by a single company, where you can spend them.