The biggest risk with rewards cards is psychological: feeling like you're "earning" money makes spending feel justified. This is dangerous.
The overspending trap. Research shows people spend 10-25% more using rewards cards, thinking cash back offsets spending. If you spend $200 extra monthly chasing 1.5% cash back, you're earning $3/month in rewards but spending an extra $2,400/year. That's a net loss of $2,364.
The interest trap. Carrying a balance at 18-24% APR is the cardinal sin of rewards card usage. If you spend $5,000 and don't pay it off, you'll pay $900-$1,200 in annual interest. Even generous 2% cash back ($100) gets wiped out eight times over. For people rebuilding credit, high balances tank your score by increasing utilization.
The redemption trap. Some cards restrict where you redeem rewards. You earn points but can only redeem them on specific websites at inflated prices, or earn miles for flights that require premium cabin bookings. Read fine print before signing up.
The annual fee trap. Premium cards ($95-$550/year) promise impressive rewards, but most people don't spend enough to justify the fee. Unless rewards exceed the fee by at least 50%, avoid it.
The utilization trap. Putting large purchases on a rewards card increases utilization. If your card has a $3,000 limit and you spend $2,000, you're at 67% utilization—high enough to damage your score by 10-20 points. Even immediate payment only helps your score the following month.
Safe approach: only use a rewards card for small, planned purchases you already intended to make, and pay the balance in full before your statement closes. Rewards are a bonus, never a reason to change spending.