Why the usual advice fails here
"Buy him a nicer version of what he has" is the standard suggestion and it rarely works, because a well-equipped golfer has already made a deliberate choice about every item in the bag. Upgrading his ball, his glove or his rangefinder isn't a gift — it's second-guessing a decision he already made, and he'll be polite about it.
The productive move is to find a category he has never had a reason to shop in. There are four, and they're reliable.
1. Practice at home
Almost every golfer wants to practice more and almost none of them do, because practice means going somewhere. Anything that removes the trip — a putting mat, a swing trainer, a garden net — is genuinely new to most people, however well-equipped.
The swing trainer in particular is the rare training aid that isn't a gimmick; you'll see them in tour warm-up bags, which is about as good a signal as this category offers.
2. Genuinely personal objects
A golfer can own every club made and still not own anything with his name on it. Custom printed balls and a ball stencil both solve that, and the stencil is the better long-term gift because it works on every dozen he ever buys rather than just one.
3. The stuff around the round
Golf involves a drive to the course, a boot full of wet shoes, and usually a drink at the end. None of that is equipment, so none of it gets bought. A trunk organizer and a good whiskey glass are unglamorous suggestions that land far better than their price suggests.
4. The specialist item he can't justify
Every golfer has a category they know they should own and can't rationalize buying. Rain gloves are the classic — they cost little, they work, and almost nobody buys them for themselves because it feels like planning to have a bad day. A push cart is the expensive version of the same idea.
One thing worth knowing
The page that ranks first on Google for this exact question is, at the time of writing, a retailer page that no longer loads properly — we checked it during research. There is a lot of thin content in this category, most of it a list of eighty products with two sentences each. Fewer picks with an actual reason attached is more useful, which is why there are nine here rather than eighty.