I got a friend who's made his living welding. Notorious for not wearing a helmet.
His neck always had a flash burn and he'd get arc eye a couple times a year.
He got cancer in his neck. Damn near killed him and he had to relearn to eat and swallow.
I was at his shop the other day, he's welding something, no helmet. I got on him about it and of course, the cancer wasn't caused by the UV light, it was something else. blah,blah,blah....
You can't tell him, he won't listen.