Interesting.

I see what you're saying about the price of a ticket that 'I would otherwise purchase', but the reality of it is, I would NEVER pay for a business class / first flight - thus why I've decided to collect miles.

It basically means I can afford something that I could never usually afford - I'm just 'paying for it' over 12 months by means of credit card spend etc.

Thanks for the comments anyway - useful as always

Andrew