Because I don't want to deal with a hundred of anything, and I don't want to deal with decimal points. I want everything I measure to be near single digit numbers. Hence, inches for common dimensions like a "2x4". I can handle something being 5 1/4 inches. How the hell large is 133 mm? Humans are not good at intuiting numbers far from unity.

Miles are great. The typical highway speed limit is about a mile a minute. You can easily lower bound how long it will take to get somewhere if you know how far it is in miles.

In cooking, I often need to halve quantities in recipes, hence pounds and ounces. Watching cooking channels give metric quantities is absolutely baffling to me. You see things like 175 mL. That is 2 sigfigs too many.