Here's a more detailed response to a good question: why use cheap safety glasses made of Chinesium? For almost all of my shooting, I use Oakley SI Speed Jacket glasses with thick ballistic lenses. I recently got fragged by about half a 9mm bullet that bounced off an edge hit on a steel plate at ~7 yds. It hit dead center of my right lens, hard enough that I felt the push into the nosebridge. Yep, I'm a believer in quality safety glasses.
For combatives, airsoft, etc., I think the Chinese cheapos are fine. I'm not going to wear a $250 pair of Oakleys on the mat. It's way too easy for them to get ruined.