When it's a harmful opinion, 'Live and let live' goes out the window.
If your opinion is that cheesecake trumps ice cream, no one should say anything. Live and let live.
When your opinion is that blondes are more attractive to you than brunettes, no one should say anything. Live and let live.
When your opinion is that gay people are morally corrupt and will burn in your religion's pit of fire because your religion's god deemed then unholy, EVERYONE should collectively hush that noise.
I'm straight.
The dog I have in this fight is that I couldn't stand seeing someone get treated lesser than me.
For example, I have a child. If I saw another child get molly-whopped by done other kids, I'm not going to get back on my phone life "Welp, my kid's over there on the swing, so we're all good."
Nah, I'm stepping in.
Same reason I'm white as hell but have always been a voice against covert, institutionalized racism.
And since I've already mentioned being straight but supporting gay rights and being white and speaking out against racism, I'll also throw in that I'm a male and an active voice in feminist issues.
"Not my problem" has NEVER been my attitude.