You're optimizing the spending that you were going to do anyway. For instance, I have to pay the utility bill no matter what; I spend about $3k/year in utilitie

You're optimizing the spending that you were going to do anyway. For instance, I have to pay the utility bill no matter what; I spend about $3k/year in utilities. I could put that spending on my 2% card and get back $60/year in rewards. Or if I take the time to do my research I could find out that by putting it on my US Bank Cash+ card, I can get 5% back which comes out to be $150 in rewards/year (a gain of $90/year). The only additional work was the 5 minutes to apply for the card, and the 5 minutes/month it takes to log in to the website, pay the card, and log out. A $90 gain / 60 minutes of work per year = $90/hour in "reward income." In practice, you don't use most of the 5% categories. Whenever a quarter with useless categories comes around, just stick the card into a drawer and check back in 3 months. You're correct that the ongoing rewards rates are typically fairly anemic overall. The real rewards in credit cards comes from the sign up bonuses. It's pretty easy to get $500-1000 of value by signing up for a credit card and spending $3-5k in the first 3 months of card membership.