Do you really want to turn $6,000 into a volatile currency over which you have no control? If you can use the miles right away for a specific award that buys a ticket for significantly less than what you would pay with cash, then go ahead and buy them. If you are just buying them because they are on sale then you hope to use them later then it’s a very bad idea. Sales pop up on a frequent basis so wait until you have specific plans to use them. You are effectively gambling by purchasing right now, and the casino can change the rules whenever they like (and they will).