Another thing to consider is that a lot of us rack up the miles very easily, thanks in part to tips we learned on FlyerTalk!
For example, all my credit cards earn miles/points. I am Premier (bottom-level elite) on United, so I earn a 25% bonus on all paid miles flown on UA. I look for other ways to earn bonuses (online booking, special offers, grocery miles, other partner bonuses, idine, the list goes on and on).
When you rack up hundreds of thousands of miles/points in a short amount of time, spending 90K miles on a business class trip to Asia or 100K miles on a first class trip to Europe doesn't seem so profligate.
Also, the unfortunately shaky financial state of many of the major airlines has been an inducement to burn miles more quickly than we might otherwise. What better way to "burn" than to fly premium class international instead of economy?
Kathy