Originally Posted by itsme
If you only value at $2.5K the ticket you pulled down as an award for 100K miles, then you are at best breaking even with the purchase of those miles at 2.5 cpm. (Buy them now at 2.5 cpm; hold them while subject to risk of devaluation through changes to FFP or airline problems; and at some time in the future redeem them, not necessarily when you want to?) When I "buy" miles by using my credit card to pay taxes, I am not looking to break even or just come out marginally ahead later when I "sell" them back, I am looking to get a doubling or more of my upfront cash "investment" in those miles.
Didn't mean to suggest I'd pay 2.5 cpm. I think I did something like that once to top off my daughter's balance with the purchase of one or two thousand miles, but that's the only circumstance in which I'd pay retail.
The bulk of my miles comes from tax payments (self-employed, so it's all estimated payments and balance due) at a cost of about 1.26 cpm, after you account for the double miles.