It’s good that you are shocked and surprised.I always knew monsters and sickos walk among us, and the OP confirms it.
That’s a normal healthy response. Unfortunately abuse like this happens often. It happens with parents, teachers, Sunday school teachers, extra curricular sports teachers, counsellors, neighbours, family, acquaintances .... even
( apparent ) friends.
AND unfortunately there are adults who purposely seek out these types of roles ( extra curricular sports, Sunday school teachers etc) so they can do this. There’s already the needed trust from the children. After a while these children start thinking it’s normal treatment for bad kids and many kids don’t share due to shame. It’s a horrible thing to do to anyone but especially to those with young, growing minds who don’t know the difference.