On the surface, Americans seem to love their rewards credit cards.

After all, 87% of all U.S. credit cardholders have at least one piece of plastic that enables them to earn travel, cash back, and other credit card-related rewards.

Once you start scratching that surface, however, the reality of rewards credit card usage is more problematic -- most Americans aren’t using the card rewards perks they’ve earned.

That’s the takeaway from a new Lending Tree study that shows a staggering 70% of all U.S. rewards credit cardholders have unused cash back rewards, points, or miles.

Of that group, the majority (49%) have unused cash back rewards, while 13% have unused airline miles and 11% unused fuel points.

That’s not all. The Lending Tree report also notes that 40% of rewards credit cardholders haven’t cashed in on any rewards in the past year.

Additionally, Generation Z consumers redeem credit card rewards more frequently than other generations, but baby boomers are most likely to do so annually. 17% of Gen Z cash in on rewards every month (or more often), compared with 11% of millennials and 9% of Gen X and baby boomers. However, baby boomers were most likely to redeem credit card rewards in the past year (65%, versus 62% of Gen Z).

Study analysts say the overriding issue with credit card reward users is lethargy.

“Obviously, you shouldn’t just redeem perfectly good reward points and miles for something that doesn’t give you good value,” said Matt Schulz, LendingTree’s chief credit analyst Matt Schulz. “However, it’s important to remember that rewards points and miles tend to be depreciating assets. They’re only going to get less valuable over time.”

Why would a credit card consumer go through the trouble of getting a rewards/cashback card, and not use the benefits accrued? Experts attribute the trend to the economy, card reward cashout confusion, and general indifference.

“We know that consumers tend to focus on three core areas when it comes to their credit card preferences: cashback, value, and rewards,” said Krista Phillips, EVP, head of branded cards and marketing at Wells Fargo. “We also know that consumer spending behavior has changed significantly in the last two years and many people are evaluating the cards that they do carry to ensure the rewards and benefits work for them.”

Additionally, U.S. consumers aren’t savvy when it comes to using their credit cards especially when it comes to rewards, other card experts say.

“Many people hold off on redeeming their rewards in order to feel like they're getting the best redemption value,” said Andrea Woroch, founder of AndreaWoroch.com, a personal finance advisory platform. "For most, the value of redemption may not seem good equivalent compared to what they spent to earn those rewards and so they may continue holding off until they feel they get the best value."

Credit card companies aren’t doing themselves -- or their customers -- any favors with overly complicated card reward programs.

“Credit card rewards programs are confusing and abstract for many people,” said Ted Rossman, senior industry analyst at Bankrate.com. “They get overwhelmed by the options (i.e., travel, cash back, gift cards, and merchandise) and don't know how to redeem.”

As consumers often take an out-of-sight, out-of-mind attitude on credit card perks, an attitude adjustment on free cash may be in order.

“Card rewards represent real money, so it's important to earn and burn them strategically,” Rossman said. “Some people hoard their rewards for hoarding's sake. But it's not like your 401(k). There's no sense in becoming a points millionaire.”

Unfortunately, credit card rewards generally lose value over time, largely to inflation and because companies devalue their programs, requiring more points or miles for that same free flight or hotel stay.

“It's best to use them periodically,” Rossman told TheStreet.com. “It's fine to save points and miles with a specific goal in mind -- like that 100,000-point first-class plane ticket for a bucket list trip -- but hoarding aimlessly is a mistake. And on cash back cards, there's really no incentive to leave your rewards unused. Cash them in as soon as possible (every month, perhaps). They're not going to get more valuable.”

It's also a good idea to review the year-end credit card statement from 2021 to see where you spent the most and then find a card that gives you more rewards for that spending category. “You can compare cash back and other types of reward cards at sites like CardRates.com,” Woroch noted.

Additionally, check your credit card emails on a regular basis -- at least once a week.

"The emails will alert you to any bonus cashback or reward offerings in any given month as you could qualify for more money back, miles, or points when you opt-in and make a purchase with that merchant,” Woroch told TheStreet. "If you're planning to buy from that retailer or spend with that merchant anyway, don't miss out on free money.”

The takeaway on ignoring credit cards? Rewards points and miles are real money, so treat them that way.

“Put together a list of how many you have and devise a plan to use them thoughtfully,” Rossman advised. “I'd say the same thing about gift cards, many of which go unused."

"They're not doing you any good just sitting in a junk drawer or buried in your wallet.”