I’m pretty skeptical of the idea that “it’s none of my business.”  It’s a cop out. 

On the one hand, it is admirable that the phrase conveys a sentiment of not judging. If it’s none of my business, I’m forgoing my ability to judge you for how you've handled your business. 

On the other hand, I’m also letting myself off the hook. If I care about you, when you are struggling or behaving in a way that doesn’t reflect your values, it ought to be my business to help you get back to being your best self. If I’m not in my brother’s business, I’ve got a loophole out of being my brother’s keeper.

So we have a choice. If I say “it’s none of my business”, I’m telling you that I'm not going to judge you. But if I say “it’s none of my business” I’m also saying that I’m not your brother nor your keeper.