No matter what you do when you decrease, the pattern is going to change toward the top of the hat. With a wide rib pattern like that, I usually hide the decreases in the knit ribs. (The early decreases are usually every other row, so it isn’t hard to do them only on the right side if you’re not used to purl decreases yet.) You can decrease six or eight times, whichever the pattern wants, on every other round until you get toward the top of the hat.
When you run out of the wide ribs to use for decreases, the pattern is going to break, but you’ll be almost done with the decreases by that time.
There’s also a hat style that has you just make a straight piece of knitting and gather it at the top without decreases. If you’re making up your own pattern, you might try that.