Important context:
The gym I go to is a powerlifting gym. Not your everyday example when you think of a gym. It's a lot smaller and the people who lift there are typically professional body builders/wrestlers/professional athletes/etc. who warm up with half the plates in the gym. However, the gym is still open to the public, so you get the occasional person who has no idea the first rules of safety in the gym. These people are typically 30s or older, as we don't see that many young people at this gym. The gym is also a 24 hour gym so a lot of the time I lift there is no employee present.
A little about me: I'm one of those rare young people. I don't exactly have the same intimidation factor as most of the other guys there, even if I can lift almost as much as them. Just because I'm not 6'5'' doesn't mean I don't know what I'm talking about. I have 5 years of professional weight training and 2+ years of teaching new weight lifters how to properly lift.
Here's where my problem comes in. Every once in a while I'll see someone perform an exercise dangerously wrong. If they continue to perform in the same way it will lead to damage that could have been prevented with proper knowledge of how to lift. As a trainer myself, I feel a big urge to try and help this person so they do not get hurt. However, I don't want to be "that guy" who goes around the gym thinking he knows everything or come off as rude. I also do not want them to take the correction in a wrong way. Because of the gym, they can get easily offended if you try to correct them because the atmosphere is if you go here, you know what you're doing. Now if someone came up to me and said "hey, you're not doing this right, try to do it this way..." I would be very appreciative of the advice. Not everyone is like this, unfortunately. Maybe this wouldn't be such a problem if my expertise was obvious from looking at me, but it's not.
How can I approach someone doing an exercise in such a way it will hurt them, without having them be put off by my offer to help? All the times this has happened in the past I have just ignored it and hope they don't get hurt. I talked to some friends and family about this and they seemed to agree that was the best action to take, but just ignoring it does not feel right. Should I continue to ignore it or is there a way I can help them?