@TonkaTrucker
There are obviously evil, highly predatory people but there are also uncaring, biased and blinkered enablers.
This. In my experience, and that of friends who've experienced abuse of any sort, including sexual abuse (always inflicted by relatives in those cases), there are some astonishingly uncaring, biased and plain blinkered enablers out there. All of the cases that I know about have been white British people whose families seemed perfectly normal from the outside. Those families have all shunned the people whose abuse they ignored, and declared them troublemakers.
Those enablers will make all the right noises about child abuse, and how vile it is to do that to someone. Until a relative/close friend of theirs is accused. Then, they'll insist, "That can't be right."/"No, not him/her"/ "They (victim/person who reports what they've seen/experienced) must be making that up." Whole families and their circles of friends will close ranks and insist that their relative/friend cannot possibly have done something so atrocious.
Of the several people I know who've experienced this, every single one of them had told at least one parent, who had silenced them by telling them if they ever told anyone else, Bad Things Would Happen to them/their sibling/s and it would all be their fault. Given that sexual abuse often happens to younger children, it's very difficult for them to work out who to trust. Society has difficulty believing or accepting that a mother or father can abuse or enable abuse of their own children, despite the evidence that some obviously do precisely that.
There really are far too many people who would prefer to ignore abuse, and look the other way, because it's not their business.
As a PP said, protecting childhood pays back over and over in society as you have healthier and happier adults, who also know how to raise healthy and happy children.
The survivors I know have all managed to raise healthy and happy families, because they knew what not to do. They're quite reasonably NC with their own families for allowing that to happen, but because the abuse happened when they were small children, they'd processed it by the time they had their own children, and so just kept their families away from their abusive relatives.
Be the person the child can turn to. Also, be the person your adult survivor friends can trust. It may be they've not reported it yet, because the conditioning to stay quiet is very, very effective. There's a very nasty dream common to survivors. They cannot speak. They'll either be trying to call for help, use the telephone, or something, and their voice simply won't come. When they finally manage to tell someone, that particular nightmare stops.