My point deals not necessarily with the value of those miles, but with the cost of earning those miles.

If you are religiously using a miles credit card for daily spend that earns you 1 mile/$, but, as you point out, the airline runs a promotion where you could buy those miles at 1cpm, then you are effectively only getting a 1% return on your spend by earning miles on that card for daily spend. Instead of banking those miles in the FF program, you'd be much better off to use a no-fee 2% cashback card (or some similar card) for daily spend, and put that money in the bank. Then when/if you need those miles, purchase them at a lower rate.

My example:

If I spend $10K on my AS visa, I earn 10K miles.

Instead, I can spend 10K on my Schwab Visa and earn $200 cash. If I need 10K miles, I can purchas them from alaskaair.com for $190, and come out $10 ahead.

It's not necessarily the $10 that is the bigger point here, as much as tying up that earning in miles vs. cash if the miles can, indeed, be purchased at favorable rates...as well as paying annual fees on mileage/points earning cards that don't offer other benefits.

You would actually have closer to $14 because of the 2% cash back on the $190 mileage purchase. Last time I checked Alaska Air had 10k selling at $275, did I miss a promo? You would probably be better off buying the ticket with the cash back card then trying to buy mileage from the airline.

For me the best way to find a price for a flight is:
sum(Earning Bucket + elite bonus + class of service bonus)/airfare.
It is a case by case basis. It is hard enough figuring out the cost of a mile in a singular program let alone across all airline programs and then compared to all reward programs. It becomes a generalization with to many assumptions.

I would say the major attraction in mileage is the big promo's. Earning 150k AA miles for purchases that were sunk costs plus the additional 1mile/$. How much would it cost to buy 150,000 miles? or 150,000 worth of award flights. I do agree that mileage cards are not the best at earning/$ but I think many are drawn by the huge promos.

some mileage programs offer perks for certain spends on their cc's or status advantages. some rewards program do the same thing for certain spending thresholds. It is a person by person decision.

Speaking of AS, often their fares to places in rural Alaska are prohibitively expensive yet there is good award availability at the low price- therefore in this case it would make sense to buy the miles here.

I see what you are saying now. Would it be more accurate to say that if you can purchase miles for less than 2 CPM, you should spend on a 2% cash back card and buy them with your cash back instead of earning them directly? (This presumes 1 MPD... of course with some cards and/or promotions, you can do better than 1 MPD.)

AS has an option with each ticket purchase to buy 10K miles for $190; however, if you buy less, they are not at as favorable a rate, and I do not believe you can buy more than 10K with each ticket. You cannot get this rate on the regular purchase miles option.

Exactly right, my point is that one should evaluate the every day earnings for every day spend on their miles/points cards. Signup and other promos are where the big miles are at. Also, if a certain spending threshold gives automatic status or EQM's, that is an additional factor that requires consideration. My point is merely to help those out there who fell victim, like I did, to assuming daily spend was best put on a mileage card...when in fact I had another card in my wallet that earned a better return (for daily spend).

Exactly right...there are, indeed, some rural routes where one could get a ticket cheaper (often significantly) by purchasing and subsequently redeeming miles on AS.

Yes...that's the basic gist. One should evaluate the return on all of their cc spend to determine that what they are doing makes sense. In the end, it might be that you use different cards for different purchases:

your miles card for purchases on your primary airline due to a 2-3x miles rate on that carrier

your hotel card for stays in that chain due to favorable earning there.

your Discover card (for example) on their quarterly 5% cashback categories

Another cashback card at restaurants and grocery stores that has a favorable rate there.

Or...look at all of your options vs. your average spending patterns and pick the one card that is likely to yield the best return if you don't want to have to think about different cards for different purchase categories.

This is all related to the value of miles because you have to have an idea of how much the miles are actually worth as a currency before you can evaluate if earning them using credit card spend is appropriate. Again...this is after the big sign up bonuses are earned...meeting the spending threshold for a big bonus is probably always going to be a good return...

I do the math on this subject on my Value of Miles page on my website below.