Ok, I'm not trying to start trouble, but there are a number of other button lock knives that don't exhibit that much wear even after a few years of use. But his explanation is that his is superior because it's designed like that? Interesting.
Yea I had the same thought.
I have 6 Button lock flippers. The oldest is a Protech Cambria, bought in fall of 2017, which doesn't have a single ding in the button, and neither do my more recent Protech button locks, the Mordax and Malibu.
I have two Spartan Pallas button locks, one of which does have a gouge in the button, because I was prying with it, put too much force on the tip, and the lock slipped. 100% my fault for pushing the design past its limits. I disassembled it and rotated the button, so the gouged out part of the button wasn't near the lockup, and now it's like new. That button hasn't rotated on its own since the spring of 2018. Looks like the button on the Sumo has rotated quite a bit since you received it. I just hope it doesn't rotate and land on an already damaged section of the button when the OP goes to use it.
My other button lock is a Rod Olson custom, that has had no issues since I bought it a year and a half ago.
P.S. it's really hard to take close up pictures of button locks with just my phone and the lighting in my house, otherwise I would have included some.