I'm annoyed by a child on my expensive higher class train ride
What are they doing? You should just try to ignore them and enjoy the ride.
They still shouldn't be there. They shouldn't live like aristocrats.
You should still try to ignore them. They are children and do not know any better. You should not get mad at them.
It's just nice to know how much of my money is going to fund a spoiled brat
I understand you wanted to just relax there, but that child's parents paid fairly for their seats so they do belong there. It's not the child's fault at all. If they really bother you, why not try asking the parents to help calm the child down?