I would not buy airline miles unless I had an immediate use for them. Buying miles now for use 14 -- or more -- years from now is a bad idea, for several years:

1. You might not be alive 14 years from now.
2. The miles accumulated in many FFPs tend to become less valuable over time because of program devaluations.
3. One or more of the airlines from which you have purchased miles might go bankrupt -- yet again. While your miles might very well still be useful if the bankrupt carrier gets taken over by another, there's no guarantee.
4. If your credit is good, and you can charge an average of $1,000/month, you should be able to reap lots of airline miles/hotel points from credit-card sign-up bonuses -- assuming that they are still offered when you retire.