Originally Posted by
wizard669
...If I am getting 5miles per dollar, I need to spend $12K for just 1 ticket.
The cash ticket on the same date is $842. If I am getting 15% cash back, I need to spend only $5600.
There is an arithmetic problem. You cannot earn 15% cash back on general spending, nor can you earn 5 miles or points per dollar on general spending. It's possible to earn large rewards on specific categories, but not across a wide range of spending.
However, your conclusion is probably correct, Miles and points seldom provide good value if redeemed for economy class airfare.