I know the dilemma.
Attitude 1: let it go, enjoy your vacation - you've only got so few days to begin with, try to avoid the groups.
This is the most practical advice, but it leaves the uncomfortable feeling you let yourself be pushed around. They go to Thunder Mountain? Then you go to Adventureland. It means they decided where you go.
Attitude 2: stand your ground, don't take nonsense from people, wear the 'don't mess with Texas' shirt.
In this scenario, you did not let yourself be deterred from riding Thunder Mountain, but it is ruined by the deafening screaming thoughout the ride.
This attitude also means means your vacation will be ruined by stress. It means that you let others get under your skin, that they ruin all of your vacation instead of small bits.
It also, worryingly, means you run the danger of becoming the 'park police' - which invariably ends badly and is best to avoid.
I have never been able to solve the dilemma. And there are more dilemmas like it on 'real life', which I have never quite figured out either. At my local zoo, which I visit very often, a lot of people feed the animals, despite signs everywhere. If I say something, I get yelled at, must run for my life, or sometimes accuse people incorrectly. If I don't say something, just walk away, I feel angry about that.
Neither option is satisfactory. Maybe the cruel truth is that people who are sensitive to their surroundings, who care about other people and their surroundings, will never be able to solve it.