Frequent flyer programmes are a scam by airlines directed to increasing brand loyalty - that is, making it more costly for a passenger to fly several airlines according to whatever offers better prices, service or destinations/times to suit the travel plans. Effectively, every time you fly, a part of the fare goes to support the frequent flyer program, which is of no use to you unless and until you have taken more flights to earn full "free" flights or upgrades or status.