I make heavy use of United frequent flier miles. I charge everything on the United credit card and have almost enough miles to fly to Tokyo every year. I buy the rest of the miles I need to get business class when United offers miles for sale periodically at yearend.
I remember when this mileage program started back in 1981. Wikipedia doesn’t give United the full credit it deserves, but Wikipedia often screws up history by finding someone in a backwoods Australian town who did the historically important thing a month before the real inventor did it.
United’s original idea was to use the mileage rewards for business customers to use at the hotels United was buying. Get its business flying customers to use the United hotels.
It didn’t work. Most business fliers used an in-house travel agent who wanted the mileage rewards used for future travel.
And that is the model that won out. Now there are so many trillions of reward miles outstanding that all airlines are trying to rein in the numbers. For filling up airplanes they have been a great success. But airplanes may be too full for comfort at this point.