It’s a fact of life for credit card reward chasers — almost inevitably, the most generous cards end up scaling back the goodies sooner or later.

A while back, it was the Charles Schwab Visa that stopped paying a 2 percent rebate. And now it’s the Costco True Earnings American Express Card. Starting Aug. 1, the cash rebate will fall to 2 percent from 3 percent for restaurant purchases. Also, people who carry a less-used “Cash Rebate” version of the card will need to spend $7,500 in a year before they graduate to a higher cash-back earning tier that is unique to that card; currently, they need to spend $5,000.

These are the only changes that Amex is making. The 3 percent gas rebate will remain on the True Earnings Card for purchases up to $3,000 each year, and there is still no annual fee besides whatever you pay to be a Costco member each year.

So why this and why now? Leah Gerstner, a spokeswoman for American Express, said that rewards were expensive and that the company needed to make adjustments given the costs associated with increased regulatory scrutiny. “We still have some of the richest cards in the market,” she added.

Which is true. But the gluttons among us will soon be paying just a bit more out of pocket to feed our faces.

Meanwhile, any guesses as to which card will see the next devaluation?