Originally Posted by eponymous_coward

You wanted to know what the least risk is. It's relatively easy to generate enough spend on a 2% cash back card that gets you $750 cash back. You also aren't entering into a contract with another party (the airline running a mileage program) under false pretenses, which is where the risk lies.

But hey, we all get to determine where our ethical boundaries are for our "hobbies" on our own... so that's fine.