Well, you're completely living off the grid at that point, to be honest. It completely ruins your life; your employer can't pay you, you can't really rent from anybody except people you wouldn't want to rent from, you won't be able to get a phone, you won't be able to get anything to do with a credit rating, and if you switch on a TV they'll just detect you again.
News stories have surfaced of people who have tried exactly that and lived off their savings in cash for twenty some years - and eventually, the courts find them, prosecute them all over again, and the fees are much higher because you tried to live above the law the first time around.
It's just TV. Nobody thinks it is worth living that way because you wanted to watch Eastenders.