Miss out on collecting miles and bonuses? But at what cost?
I have no problem using miles for myself. A flight from central MN to FAI costs almost $900 round trip. Even if I drove to MSP and flew from there, about $800 round trip - in economy. If I paid for that ticket, I would earn about 12,000 miles. But I use 25K miles for the flight to FAI and I can use that $900 to go to Europe - just about twice in the winter, earning me far more miles and value than paying for a ticket to Alaska just to "earn miles."
This is an excellent point, and using opportunity cost to assess the decision at hand is a winning strategy.