The PayPal debit card lets you choose a 5% cash back category every month. Gas, restaurants, and a few other I don't remember. It's a much better deal than most of the credit cards I carry.
It’s definitely less than 4x points back I get on groceries and dining on my Amex Gold.
The reason that companies are willing to pay higher credit card exchanges for Amex is because Amex users on average are bigger spenders.
But even Chase Visa cards that transfer to Hyatt hotels and you can get 3x back for groceries (by paying with grocery store app so it counts as “online groceries) you’ll get more than 5% cash back.
Then there is the whole r/awardtravel hacks of getting cheaper flights by transferring points to partner airlines like booking Delta domestic flights via AirFrance.
It has absolutely nothing to do with how much American Express cardholders spend and everything to do with what they charge vendors and some vendors or their payment processors accept Amex, or you don’t have a choice.
I know this because my firm accepts American Express and they are absolutely not our biggest spenders, but our downstream processors force us to raise prices.
Every Amex cardholder knows to carry a non Amex card. You wouldn’t lose business by not accepting them and some vendors don’t even domestically.
I can’t find stats for other cards. But here is the average wealth and income of Plat holders
https://monkeymiles.boardingarea.com/whats-average-household...
Amex cardholders are the highest earners in the industry.