316 rusts also. They call it "stainLESS" and not "stainPROOF" for a reason.
316 has more Chromium than other blends, but it still has iron in it and thats what rusts. All iron rusts and there’s nothing you can do to it to make it not rust.
I’ve welded 316 at the shop for clients and it stays rustless for many many years for use around the farm, but when you throw saltwater into the equation, and on a regular basis, that’s a different story.
If you rinse your 316 hex wrenches with water and dish detergent after every use and dry them, you will be able to be rustproof for many years.
But ideally, If it was me, I’d buy the titanium and only buy it once VS buying 316 every few years. It’s just a hex wrench. Nothing to break or go bad on it. If you bite the bullet and buy titanium you’ll still be using the same hex wrenches 50 years from now.