Fellow-travellers on trains are fucking rude by default. I've accepted this is the way things are going to be (infuriating I know), and never board without earphones and loud rock music available on a device, or without burying my nose either in work or a book.
This drowns out most of it. But last week it still didn't wholly shut out the carriage on my London train reeking of Stella and Prosecco BEFORE 10 AM, or drunken sad-sacks swaying down the aisle and jostling into me or treading into my feet (tucked under the seat, not blocking the aisles).
On the return trip I was asked to move from my reserved seat to make way for a couple who wanted to sit together (refused), and toward the end of the journey was subjected to one bloke slurring incomprehensible garbage a couple of seats down, and another one somewhere behind me making train noises! (Yes I jest you not).
First-class is no protection against horrors like this: just as frequently, it happens there too.
YADNBU.