A sense of entitlement

Why do so many people have a sense of entitlement?

I was discussing this with a friend at the weekend and we couldn't really get to the bottom of it, other than perhaps it's just been a slow erosion of society and work ethic.

They don't work, but are entitled to (net) taxpayers money, so they can have things that taxpayers can't afford, to live in areas that those taxpayers can't afford, to have holidays, to not work a job they don't want to, to be entitled to an easy and well paid job. That they have "rights" that must be treated as gospel, but not any responsibilities that are tied to those rights. That rules are just for "someone else", a whole attitude that everyone else owes them a living etc. 

What is the flawed mental process where people decide that they are entitled to things just because they want them? How can anyone even attempt to justify that "want" means "entitled"?