Aye, if the price raises the question 'how much would a private jet set me back anyway?', 10-20 percent off is not a bargain. On the other hand, if you are going to spend that kind of money on miles, your 600 euro investment bags you 0.25 euro cents/mile. If you do it twice in a year, it's 0.125 euro cents/mile. All you need is to have the other 2 million miles, but if you buy those at the discount rate of 1.5 cents / mile, and take a round-trip upgrade, you're paying €13,400 instead of €16,000, plus a regular economy ticket. So you get, on average, €2000 profit on just that one feature!