Just found out I make $30k more than a coworker who has much more work and responsibilities than I do. She’s too timid to bring it up to management. Do I stick up for her – and the rest of the team?

I think it's incredibly unfair that I make more than she does, yet she is doing far more work than I do – including travel for work. She literally cried when I told her my salary. She was grandfathered in when her previous company was bought out, whereas I was hired on separately. She is too timid to bring it up to management, thinking they won't even do anything about it and convinced that if she threatens to leave, they'll show her the door. Should I write an email to my boss to stick up for her – and the rest of the team, who I now know all make significantly less than me, despite having the same title? Will that either come back to bite me or reflect poorly on me? Is this just overwhelmingly none of my business?