Is there a seat stealer on literally every flight???

Woman in front of me had to argue with the lady that stole her seat. She just kept saying “it doesn’t even matter at this point.” wtf. Flight attendant had to come over and explain to her that the seats are assigned.

The back 10 rows (where the stolen seat and her assigned both were) don’t even have middle passengers so the stolen seat wasn’t even better. Unbelievable.