Some people think it's all about them, them, them. An entitled voice is the perfect representative of those entitled, conceited individuals that blow kisses at themselves every time they pass by a mirror, and think they deserve better than anyone else.
There are individuals who, for some reason or another, think they're practically royalty. The entitled voice is all about representing that holier-than-thou spirit of those who think they hover above the rest. Whether it's by birthright, or by some accomplishment or other, characters with an entitled voice have an air of arrogance and disdain for others that audiences just love to hate.
Whether it's a haughty aristocrat, or a pirate who sails the seven seas, the entitled voice is a mainstay of works of fiction. Bad guys especially tend to have this voice, as they're the ones who are there to be brought down from their pedestal when the good guys win the day. There are other times when one of the heroes is arrogant and boastful, and they will (hopefully) see the error of their ways by the time the story is over. On the marketing side, entitled voices are perfect foils for savvy characters who make them look ridiculous.
The entitled voice is generally higher-pitched, and tends to ooze a sense of being owed something. Sometimes it can also display many posh, high-society affectations that lend it an even greater sense of superiority.