I'm not saying the LCC carriers are exempt from such passengers but they are by no means the root cause or the only ones to have this problem, some people who fly often think they are owed the World and really kick up a fuss when they don't get it.
I've only had to offload someone from a flight once, being a group of 4.
One of the pax was agressive to the CC, so I went and told him myself I didn't want him on the flight.
They were very drunk already and the easiest way to deal with it would have been to deny boarding in the first place, but that's just me. They were booked on the one that evening once they'd sobered up.