Why become a stand-up comedian? For most, it is presumably fame, self-gratification, and glory. But what about the comedian who is painfully aware of the fact they most likely will never achieve those things? You know, the ones who aren't so delusional and realize they are propelling themselves into a world that is generally unamused, and into a public that is itself a clamorous organism, volatile and defensive, unpredictable and uninviting. It's this type of comedian, as self-defeating as so many others are delusional, who is the focus of Rick Alverson's "Entertainment," a movie that sits and stares at a mediocre stand-up comedian for 90 minutes and refuses to look away.