Credit cards exist to monetise your spending. Every time you pay with a card, the bank earns from the merchant. To keep you using their card instead of a competitor’s, banks offer you a cut. That cut comes in two forms: cashback or reward points. Reward points can be converted to air miles, and air miles can be redeemed for flights. Spend on the right cards, accumulate miles, fly for “free” (minus taxes and fees). Ten years ago, I started collecting air miles in 2016. My first business class redemption was to Taiwan in 2018. Over 10 years, I’ve earned more than half a million miles and flown to destinations on both business class and economy class flights. In 2023, my wife and I spent about 45 days overseas. Eight flights each, mixing economy and business class. Our Thailand trip in early 2026 lasted 28 days, and we paid only fees and taxes for our flights. My miles come from regular spending. Groceries, food delivery, online shopping,...